I would welcome a discussion on this concept also, I definately struggle when I check back flops. I seem to either get blown of my hand or call down and they seem to have it. I don't like the idea of betting to "see where I'm at" but often find I'm doing this

The player type you're up against matters a lot. Against passive players you can c-bet more, because they won't give you many tough decisions with in-between holdings. So you are free to bet more hands against them that you would check back often against an aggressive opponent to avoid getting check-raised off decent equity.

Aggressive players also bet more turns after you check back flop, and will exploit you if your range is very weak. Passive players do that much less, and you'll get more free cards and turn-or-river bluffing opportunities with your weak check-back range.

Against an opponent who is so weak that you can get away with betting everything on certain boards, you just bet everything. You don't have to design a balanced check-back range everywhere. But against good players you need one, and then you should put some thought into its design.

I also have got a feeling for this, hands that seem good to barrel many turn cards, but also medium strength and could be checked.  I also need to start paying attention to who I'm playing against!  At the moment I mainly just base my decision around the board and how I think that hits villain's range compared to my hand.

Well it's bad to just cbet every board so I check back very wet boards with air. Also a good indication is a mediocre hand that can improve on the turn alot but can't call a raise on the flop. Next to that, you also want to keep the pot small sometimes. 

The best hands to check back, are hands with lots of potential, but which are weak right now, you would hate to get x/r off your hand and there is a decent number of turns on which you improve. on the other hand, I would cbet hands that don't have much potential, but do have some strength already. Actually Zenfish wrote a really nice blog about which hands to bet on a paired board in which he explains a few concepts on how to build our cbet range in general as well.

My default line IP in HU or three way pots is to c-bet.  When deciding if a check back might be better I ask myself:

1. How likely is a c/r from this opponent (i.e. ZenFish's point that if you're likely to get c/r off your equity you should be much less likely to c-bet); and

2. How strong is my hand now/what potential does it have on the turn.  Hands that you would like to see a turn with but can't call a c/r seem perfect candidates to check back (e.g. a gutshot and backdoor FDs). 

I think against weak opponents the "bet everything" strategy works so well that you can really out-think yourself by checking back too much. But it's definitely good to be prepared with a less exploitable strategy against tough opponents.

I wonder if another useful way to think about it would be to look for hands whose equity changes a lot on the turn. For example, a hand with strong backdoors is going to be nothing on some turns, but pick up very strong backdoors on others. Whereas something like two pair is going to be medium-strong on most turns. With hands whose strength is likely to change a lot it might be more useful to see a turn before putting money in the pot.