Pushing out trips when I and another guy have a flush?

[Nielsio]

I turn the nut-flush. I can put Doug on a turned flush also, but there's a third guy, who showed a little strenght on the flop but slows down when 3-flush hits. The river is an easy fold, but I could have played it quite differently. What happened is I wanted to check-raise the other flush huge on the river. Obviously, a scare-card could come off but I'd like to play these multiway hands passively, because I know it's almost impossible to get two pairs and trips out of the hand, so I'd like to wait to the river. Same thing when I hit trips on a straightish board multiway. I tend to let cards come off and hope for a boat because there's little chance of raising straight-draws out of the hand (or knowing if they already have a straight or not). So I gamble a bit by letting cheap cards come off.
In the case of the flush-hand there's about a 25% chance of the board pairing.
In retrospect I could positively put Doug on a flush and could have put the turn all-in (or similar), as last to act. I can also just build the pot earlier because a paired board can scare the other flush, but I don't like the idea of the third guy sticking around and facing a tough decision with a big pot. If the board wouldn't have paired here I would have taken a lot of Doug's money. So what way would you prefer and do you guys have success pushing trips out?

Mook is 40/2.2/1.31 loose/passive/passive fish

Seat 1: Nielsio6 [ K[img]/images/graemlins/diamond.gif[/img],Q[img]/images/graemlins/diamond.gif[/img] ] ($40.50 in chips)
Seat 2: doug88doug ($50.65 in chips)
Seat 4: ianmcc0 ($29.50 in chips)
Seat 7: jj Mook ($52.75 in chips)
Seat 8: khammer6 ($49.25 in chips)

ANTES/BLINDS
Nielsio6 posts blind ($0.25), doug88doug posts blind ($0.50).

PRE-FLOP
ianmcc0 calls $0.50, jj Mook calls $0.50, khammer6 folds, Nielsio6 calls $0.25, doug88doug checks.

FLOP [ 7[img]/images/graemlins/club.gif[/img],A[img]/images/graemlins/diamond.gif[/img],3[img]/images/graemlins/diamond.gif[/img] ]
Nielsio6 checks, doug88doug checks, ianmcc0 checks, jj Mook bets $1, Nielsio6 calls $1, doug88doug calls $1, ianmcc0 folds.

TURN [ J[img]/images/graemlins/diamond.gif[/img] ]
Nielsio6 checks, doug88doug bets $2, jj Mook calls $2, Nielsio6 calls $2.

RIVER [ J[img]/images/graemlins/spade.gif[/img] ]
Nielsio6 checks, doug88doug bets $5, jj Mook bets $15, Nielsio6 folds, doug88doug calls $10.

SHOWDOWN<font color="white">
jj Mook shows [ 3S,3H ]
doug88doug mucks cards [ 5D,4D ]
jj Mook wins $40.

SUMMARY
Dealer: khammer6
Pot: $41 | Rake: $1
Nielsio6 loses $3.50
doug88doug loses $18.50
ianmcc0 loses $0.50
jj Mook bets $18.50, collects $40, net $21.50
khammer6 loses $0</font>