Couple of ZONE hands, so no reads are available. I'd love some feedback on the hands though.

Hand 1

Eff $300

Hero (UTG) opens TcTs to $5
Villain (BTN) 3bets to $17.50
Hero calls

Flop: 6d 8h 4c

Hero check calls $20

Turn: 9h

Check / Check

River: 2h

What's our preferred play here?

Hand 2

Moreso curious to hear how you guys might play this spot differently. It's very weird to me and I wasn't really sure what to do. I hated calling down but the bet sizing led me to keep doing it.

Eff $400

Hero (UTG) opens AsJc $5
BTN calls
SB calls

Flop: Ah Tc 8s

SB leads $6
Hero calls
BTN calls

Turn: Ks

SB bets $12
Hero calls
BTN calls

River: 5d

SB bets $15
Hero calls
BTN calls

SB shows As4s
BTN shows AQo