Party 25NL (6 Max) - 2 pair facing river push on weird board

[payoff wizard]

Only my 5th hand against villain. No read obviously.

Party Poker No-Limit Hold'em, $ Hero (5 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver)

SB ($15.85)
Hero ($49.50)
UTG ($24.55)
MP ($19.80)
Button ($30.10)

Preflop: Hero is BB with A, 4. SB posts a blind of $0.25.
UTG calls $0.50, 2 folds</font>, SB (poster) completes, Hero checks.

Flop: ($1.50) 2, 4, A(3 players)</font>
SB checks, Hero checks, UTG checks.

Turn: ($1.50) 6(3 players)</font>
SB bets $1</font>, Hero raises to $3</font>, UTG raises to $6</font>, SB folds, Hero calls $3.

River: ($14.50) T(2 players)</font>
Hero checks, UTG calls $24.55 (All-In), Hero ????????

I'm thinking I should have bet the flop, but I was pretty sure I was a mile ahead and so didn't want to kill my action. Comments on all streets welcomed.