CO: $550 New to table. Quiet guy in early 40's with sunglasses.

BTN: $760 Weak-tight 10/5 reg. Seems to take check/call lines post flop with range of mid-pair to nuts. Am assuming he bets/raises for protection only & never for value.

SB: Hero $760. Been card-dead in first hour so I probably look extra nitty. Been taking some pots uncontested and have been 3betting V on BTN pf about once every 40 minutes.

BB: $760 Mid 40's reg from Europe spending about 6 months at this casino. He switches between TAG and LAG but has been mostly TAG this session. Doesn't seem like a pro, but a winning player that works on improving his game. Capable of bluffing. Doesn't slowplay. Noticed a leak in him calling 2bet and 3bet AI flops w/ just an overpair in spots where it was obvious his opponent had better. Also doesn't follow the game but watches poker hands on his phone. Talks about hands with other off-table regulars in the house. Likely thinks my pf range is strong. Has seen me play flopped FD's aggressively. Probably assumes that my bluffs are in position.

CO opens $20, BTN call, Hero call KJ, BB call.

Flop: $74

KQ7

4 checks. Wouldn't mind input here. Vs 4 players I'm really hopping to improve & keep ranges that pump the pot as wide as possible. I felt to charge draws, I'd need to bet large which could bring RIO.

Turn: $74

J

Hero leads $40, BB calls, fold, BTN calls Not sure if wise, so please comment. Wasn't clear on what I wanted. I felt while this completes many draws but also opens up several others. I feared another 4way check, but again, RIO.

River: $193

7

Check, BB bets $120, BTN folds, Hero?

Flop looks okay. I'd donk this flop if your opponents were bad and passive. Doesn't seem to be the case here.

There's a lot of value on the turn. Bet larger. I'd make it 60. The players in position didn't have much on the flop. Plenty of hands will pay off.

On the river, we need to be good about a third of the time. If you've been paying attention at the table this is going to be a lot easier. You might be able to answer questions like:
-Does BB play Axo type hands? Could he have Ad7x or a bare Ad that missed on the river?
-Does BB call pre-flop with medium suited connectors like 97dd? How about bad suited connectors like 42dd?

From your post it sounds like villain is capable of bluffing, and this is a good spot to bluff. You bet small on a wet board and another player just called. Your hand looks weak and so does the caller's. He probably thinks you were semi-bluffing and have given up. In a vacuum I'd expect villain to raise turn with some flushes and to have a variety of hands in his calling range, such as single diamonds, pair + straight draw, etc. I would call.