Almost nobody in the Eastern-European countries speaks proper English. Western-Europe is probably a better option.
Also, the East is far less wealthy, and there's way more crime and shady actions by their governments.
Unless the Eastern countries appeal to you more, I'd definitely look into countries such as Germany, Belgium, The Netherlands, Scandianavian countries (if you don't mind freezing your ass off), Austria, UK etc.

I'm trying to avoid everywhere except eastern Europe, my choice here was deliberate as I feel the culture in other places is far too 'American-ized' and that I won't be any more happy there than I am here.  Speaking completely proper English is not a requirement, all I need is a minimal amount, enough that I can communicate on a relatively basic level.  I've heard from a number of different people that the majority of people living in Bucharest, Prague, Budapest, etc, all speak a reasonable amount of English.  Regardless, wherever I go I'm definitely going to be willing to spend some time learning a bit of the native language.

Amsterdam dude, everyone speaks english!

If you get around to Bucharest/Romania you need to try out Cluj Napoca. Way better city then Bucharest. Won't regret it! People are way different then the capital and you will pleasantly surprised I can promise you that!(ask your friend from Bucharest)

And I like to add: Chael you are a bit off about "Almost nobody in the Eastern-European countries speaks proper English" !

Hi I m from Bratislava, Slovakia. Its a half million capital city. everything is cheap here when u compare it with the western EU. If u want to stop by here for a few days just let me know i ll show u around and also if u want to go to Prague I have a few friends there so we can spend a few days there as well. I think in all Eastern EU countries young people under 30 yrs can speak english at communicative level, its much more better than 10 yrs ago...

Going to live in a completely new city without knowing people there already is hard. I think the people around you more than certain aspects of a country's culture or your physical surroundings will determine your happiness. I think maybe you should let us know about other stuff you are interested in because that will allow you to go to a new city and find like minded people. Unless of course you plan on being a recluse. For example I used to play a lot of basketball and when I went to live in a country by myself one of the first things I did was go find a basketball club and people that liked playing. Stuff like that helps overcome language barriers as well. Also when choosing a country, consider things like if you wanted to learn a language, which language would you like to learn most. In most major cities in the East of Europe (sorry but I really detest the loaded term Eastern Europe) a decent amount of the population, especially young and those working in the service industry, will speak English. To be honest, I think you need to give us more information on what kind of things you are looking for/are important to you etc. It is kind of like a Polish or Romanian person saying "I am thinking to move to the US, which state should I move to?"

Sorry only just read your reply to the other post where you mentioned learning some of the native language? Have you ever learnt a foreign language before? This could actually make a difference to where you choose to live. Hungarian for example has something like 18 cases. Also, from my personal experience, people really appreciate when you make the smallest attempt to speak to them in their native language; even when doing something simple like buying bread and as a result will make you feel more welcome. May sound silly but these little things can make a big difference if you plan to live in a completely new country.

Hey,

 I'm from Romania. I don't know exactly what you are looking for. If you want rest and peace i can recommend the place where I live wich is a small town called Piatra-Neamt, one of the oldest cities in Moldova with an age of 2000 years (former Dacian place). It is known as the Pearl of Moldova because of its beauty. With its cozy streets and coffee shops, warm people and antique boutiques Piatra-Neamt will make u feel like home. It is surrounded by mountains and is one of the most beautiful and vibrant cities in Moldova(wich is an area of Romania) some may say, perhaps all of Romania. You def have a lot of stuff to visit around and it's small and cute, you can do all kind of stuffs in winter and summer too. 

150 seconds in Piatra-Neamt : https://www.youtube.com/watch?v=hFvwuUoi03w  Enjoy :)

If you want nightlife, Bucharest it's the most active town here. If u want nice places to visit you can go to Brasov at ~ 190km from Bucharest, Sighisoara, Sibiu. Also Danube Delta at the seaside it's something very nice that worth visiting.

I can show u arounds if u come with pleasure. If u need any kind of infos, you can send me a message or i'll check out here later.

Peter I am from Slovenia (nobody knows where we are but it is among Italy, Austria, Croatia and Hungary). I have lived in some of the capitals in eastern europe. I recommend you try Warsaw. You will have great life there, the city simply has everything. ( good prices, great fun, great girls, easy to find good apartment etc...)You should not worry about english, because everybody speaks decent english these days. If you will travel across Slovenia let me know and we can have some fun. Just saw you want to choose Romania, Serbia or Montenegro. In Serbia Belgrade is the only option, but you will need more time to adjust than in Warsaw. In Montenegro you want to spend the summer in Budva, but you can t be there in winter. Check out Croatia, some great places there, specially for summer.

I've been seriously considering moving to another country myself, Peter, may I ask what the draw is for you? My biggest reason is obviously online poker, but I also want to get out and see the world and try new things. I've never been out of the US at all, so kind of lost on where to even begin.

On weekends I'll usually have some girls come by and party or hang out and drink with them, on weeknights, if there's no interesting NBA games, I'll start to grind around 7 or so until I feel like quitting which usually happens anywhere between 8-midnight.  Then I drink til I pass out around 3 or 4 so I wouldn't say I have a lot of hobbies or anything, but this is what I do.

Sounds like a good life, but the drinking will catch up to you sooner or later. I know from experience and replacing drinking with other fun stuff is not the way to quit drinking, again I know from experience. But shit, have a blast and I hope things go great for you.

Peter,

One of the most important things for you to look at for all the countries you are considering is visa requirements for US citizens. Depending on the place this may make a difference to how long you can stay somewhere without leaving the country and if you are playing poker you should look at the tax situation in various places. Some won't care other might. If you plan on staying anywhere for a long period of time you may have to show them a bank balance or income and explain that income. I don't know the answers myself, but I know from experience it is often a ball-ache figuring out all the paperwork and bureaucracy so thought you might want a heads up so you can get a head start and collect all the relevant information.

First off Peter, I don t know what kind of research you performed in order to narrow your options down to Romania, Serbia and Montenegro, but you have the wrong information. Serbia and Montenegro are unstable, corrupted, poor countries, people are very cold to outsiders and have a deep sense of pride in their national heritage. You will stick out like a sore thumb. If you want to move to ex Yugoslavia, try Ljubljana in Slovenia or some nice places in Croatia. These 2 countries are much much more developed and open to foreigners with functioning social system. Even better is that Slovenia and Croatia  are so conveniently placed on the map such that you can travel to neighboring countries Austria, Italy ,Hungary, Serbia and be back on the same day.

If you decide to go to Serbia, Belgrade is the only option because it is the capital and the only place with any action and every other place is a dead zone and it won t accommodate your needs.

Budva in winter is a ghost town with nothing going on.

Don t know much about Romania, but I know some people who have been there and I suggest you do more research.

You will need more time to adjust in Serbia or MoNtenegro than in Warsaw for example because these countries are not so multicultural and as I said before not so foreigner friendly.

I'd highly recommend Budapest. There is a facebook group for professional poker players living in/planning to move to/planning to visit Budapest: Budapest Meetup for Distinguished Gentlemen of Extraordinary Aptitude 
You'll find a bunch of helpful people there.

Budapest is cheap, beautiful and many people speak english (mainly younger people). Thread from TripAdvisor (2010): 

In most areas that tourists venture, most people speak more than enough English for you to get by comfortably. I speak no Hungarian and have been spending 2-7 months each year there (and have renovated 6 apartments with a myriad on contractors and bureaucrats) and have never had a problem.

I've helped a number of foreign people to find their destinations, I'm sure other hungarian citizens are as friendly and helpful as I am. I've never experienced hostility towards foreigners.

Hey Peter,

First off my English is not perfect, but I'll give my best. I am from Belgrade and I'm 23 years old. I see you are planning on visiting, so if you have any questions or concerns about Belgrade or Serbia in general I`ll be happy to help.

Also I spent couple of summers in Montenegro (specifically Budva and Herceg Novi), and although I'm not the expert for Montenegro I can give you some information....

Hi Peter, have you been to Malta?

Hey Peter,

I live in CA north bay and I'm native of Belgrade Srbija. I would be more than happy to give you few contacts that would help you get situated quickly. Language should not be an issue as most of population 40 or younger has basic understanding of English. Its a party town that doesn't get going till about midnight.

Its all about Norway, Peter: Heres your chance to become quasi-famous. We got a tv show thats called Everything for Norway. Its about americans tracing their heritage back to Norway and competing in series of tasks with the first prize winner getting to meet his or her relatives. Maybe you got some old bloodlines tracing back to the vikings. Go for it. 

If you plan to visit Brno, Czech Republic, message me if you want.