river play with a set (6 handed $400 NL)

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Taking a shot at the Party 400 game, my usual game is the 100 NL (the $200 wait lists and general poor games have led me to this - just 1 table of 400 now and again while 3 tabling the 100s to cover the jump).

Party Poker No-Limit Hold'em, $4 BB (6 max, 6 handed) converter

PT stats for UTG: 19 / 6 from about 30 hands, so seemingly tight and decent, no other reads.

Button ($244.5)
SB ($1120.4)
BB ($374)
<font color="#C00000">UTG ($396)</font>
MP ($251)
Hero ($592.2)

Preflop: Hero is CO with 3[img]/images/graemlins/club.gif[/img], 3[img]/images/graemlins/spade.gif[/img]. SB posts a blind of $2.
<font color="#CC3333">UTG raises to $8</font>, <font color="#666666">1 fold</font>, Hero calls $8, Button calls $8, SB (poster) calls $6, BB calls $4.

Flop: ($40) J[img]/images/graemlins/spade.gif[/img], T[img]/images/graemlins/spade.gif[/img], 3[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(5 players)</font>
SB checks, BB checks, <font color="#CC3333">UTG bets $16</font>, Hero calls $16, Button folds, SB folds, BB folds.

Turn: ($72) 2[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">UTG bets $16</font>, <font color="#CC3333">Hero raises to $100</font>, UTG calls $84.

River: ($272) K[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(2 players)</font>
UTG bets $272 (All-In), Hero ?

Is not rasing the flop inexcusable?

Given how I played it, what's the river play?

Thanks a lot.