Customizing strategy to the opponent: The passive river guy

I'm really conflicted about my play in this situation. The more I think about it the less decisive I feel, so I'm posting it here.

Background

UTG is loose passive, but especially so on the river. OK, I'll admit my read is shaky, since I've only seen the guy a little while, but what struck me is how passive he plays his big hands.

This was the relevant hand:

PokerStars 3/6 Hold'em (5 handed) converter

Preflop: Hero is BB with 7[img]/images/graemlins/spade.gif[/img], T[img]/images/graemlins/spade.gif[/img].
UTG calls, <font color="#666666">3 folds</font>, Hero checks.

Flop: (2.33 SB) A[img]/images/graemlins/spade.gif[/img], T[img]/images/graemlins/heart.gif[/img], 6[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">Hero bets</font>, UTG calls.

Turn: (2.16 BB) 4[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">Hero bets</font>, UTG calls.

River: (4.16 BB) A[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">Hero bets</font>, <font color="#CC3333">UTG raises</font>, <font color="#CC3333">Hero 3-bets</font>, UTG calls.

So he waited until the river to raise me, hoping I had an A. When I 3-bet I can only think he is afraid of the very few combinations of Kx-Qx[img]/images/graemlins/spade.gif[/img] (see results) . Very few combos there. Seems like overly cautious play to me. I could have paired one of those rags and think he's bluffing, or could have a crappy A, like A2-A4, and have not raised. He probably wouldn't have raised a weak A PF in this situation.

Final Pot: 10.16 BB

Results in white below: <font color="#FFFFFF">
Hero has 7s Ts (flush, ace high).
UTG has Js 5s (flush, ace high).
Outcome: UTG wins 10.16 BB. </font>

Final Pot: 10.16 BB

Somewhat Complex Application

UTG from previous hand is now SB. What aspects do you like or dislike about my play in the following hand? There are points I like and those I don't. Unfortunately, it wasn't heads up, so there are many considerations.

PokerStars 3/6 Hold'em (6 handed) converter

Preflop: Hero is Button with J[img]/images/graemlins/spade.gif[/img], 8[img]/images/graemlins/spade.gif[/img].
UTG calls, <font color="#666666">2 folds</font>, Hero calls, SB completes, BB checks.

Flop: (4 SB) 7[img]/images/graemlins/diamond.gif[/img], 9[img]/images/graemlins/club.gif[/img], T[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(4 players)</font>
<font color="#CC3333">SB bets</font>, BB calls, <font color="#CC3333">UTG raises</font>, <font color="#CC3333">Hero 3-bets</font>, SB calls, BB folds, UTG calls.

Turn: (7 BB) K[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(3 players)</font>
<font color="#CC3333">SB bets</font>, UTG calls, Hero calls.

River: (10 BB) 7[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(3 players)</font>
<font color="#CC3333">SB bets</font>, UTG folds, <font color="#CC3333">Hero raises</font>, SB calls.

Final Pot: 14 BB