AKo, TPTK, Flush Hits Turn

[AtlChip10]

Once again, no read on players involved...

Party Poker 1/2 Hold'em (9 handed) converter

Preflop: Hero is MP1 with A[img]/images/graemlins/club.gif[/img], K[img]/images/graemlins/heart.gif[/img].
UTG calls, UTG+1 folds, <font color="CC3333">Hero raises</font>, MP2 folds, MP3 folds, CO folds, Button folds, SB folds, BB calls, UTG calls.

Flop: (6.50 SB) K[img]/images/graemlins/club.gif[/img], 7[img]/images/graemlins/spade.gif[/img], 6[img]/images/graemlins/spade.gif[/img] <font color="blue">(3 players)</font>
BB checks, UTG checks, <font color="CC3333">Hero bets</font>, BB calls, UTG calls.

Turn: (4.75 BB) 9[img]/images/graemlins/spade.gif[/img] <font color="blue">(3 players)</font>
BB checks, UTG checks, <font color="CC3333">Hero bets</font>, BB calls, UTG calls.

River: (7.75 BB) J[img]/images/graemlins/diamond.gif[/img] <font color="blue">(3 players)</font>
BB checks, UTG checks, Hero checks.

Final Pot: 7.75 BB
<font color="green">Main Pot: 7.75 BB, between BB, UTG and Hero.</font>

Am I correct to check the river here, or do I bet for value? With no read, I tend to get very passive and check almost exclusively in this situation. Not sure if this is actually correct or not...