OOP Nut flush draw in a huge pot

[gh9801]

Party Poker 5.00/10.00 Hold'em <font color="#0000FF">(10 handed)</font> link

Preflop: Hero is SB with J[img]/images/graemlins/heart.gif[/img], K[img]/images/graemlins/heart.gif[/img].
<font color="#666666">2 folds</font>, <font color="#CC3333">MP2 raises</font>, MP3 calls, CO calls, <font color="#666666">1 folds</font>, Hero calls, BB calls.

Flop: (10.00 SB) 7[img]/images/graemlins/club.gif[/img], A[img]/images/graemlins/heart.gif[/img], 4[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(5 players)</font>
Hero checks, BB checks, <font color="#CC3333">MP2 bets</font>, MP3 calls, <font color="#CC3333">CO raises</font>, <font color="#CC3333">Hero 3-bets</font>, BB calls, <font color="#CC3333">MP2 caps</font>, MP3 calls, CO calls, Hero calls, BB calls.

Turn: (15.00 BB) J[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(5 players)</font>
Hero checks, BB checks, <font color="#CC3333">MP2 bets</font>, MP3 calls, <font color="#CC3333">CO raises</font>, Hero calls, BB calls, MP2 calls, MP3 calls.

River: (25.00 BB) 9[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(5 players)</font>
<font color="#CC3333">Hero bets</font>

Comments on all streets appreciated. Most curious about the turn though. Do I bet out? And what the [censored] does everyone have?

And the river... go for a check raise, or bet hoping BB or MP3 made a worse flush?