I haven't played much NL in awhile so decided to sit in a 200NL 6max table. Just wanted to see what people think is the best play in this situation.
(The converter tool isn't working for me so i apologize for the lack of colors)

(6 max) (No DP) (Real Money) -- Seat 2 is the button
Total number of players : 6

Seat 2: nbdgolf ( $812.95)
Seat 3: Egarim10 ( $318.85)
Seat 4: early_man ( $200)

Egarim10 posts small blind (1)
early_man posts big blind (2)
** Dealing down cards **
Dealt to Egarim10 [ Kh, Kd ]
2 folds.
nbdgolf calls (2) on button
Egarim10 raises (7) to 8
early_man folds.
nbdgolf calls (6)
** Dealing Flop ** : [ 4c, Qd, 9d ]
Egarim10 bets (12)
nbdgolf calls (12)
** Dealing Turn ** : [ 5d ]
Egarim10 checks.
nbdgolf bets (20)
Egarim10 calls (20)
** Dealing River ** : [ 3c ]
Egarim10 checks.
nbdgolf bets (50)
Egarim10 calls (50)
** Summary **
Main Pot: $180 | Rake: $2
Board: [ 4c Qd 9d 5d 3c ]

Reads: nbdgolf just won 2 huge pots. First one he ended up calling a huge bluff on the river with 2pair when the river filled an oesd. It was a bad call that turned out good. Then he got all the money in with tptk aq vs 2 flush draws and took about 200 from each person. The action was heavy on the flop and he stuck with his top pair which turned out right... He hasn't shown any bluffs but i knew he was capable of it now that he has a huge stack.

Well, it worked out for you because if you bet the turn he would probabally have folded. As far as what i would do though i would bet this turn because he may check behind you with a draw or an ace both of which could take it from you on the river. JMO.

I checked the turn for several reasons. I felt if he hit the flush he'd raise me and I'd end up putting a lot of money in with the worst hand. I thought he was looking to bluff or semibluff raise me on the turn card and with the flush draw being filled I wouldn't be able to raise back which would put me in a tough decision since I'd be faced with a big bet on the river. Also I thought I could induce a bluff by checking the turn. Of course the biggest problem with checking was that it gave him a chance to outdraw me. I had him on something like qj which would mean he had 4 or 5 outs.