10nl 6max: Did I misplay AK TPTK?

[a nonymous]

$0.10 BB (6 handed)

BB ($2.35)
UTG ($13)
MP ($13.55)
CO ($9.95)
Hero ($22.65)
SB ($5.25)

Preflop: Hero is Button with A[img]/images/graemlins/club.gif[/img], K[img]/images/graemlins/diamond.gif[/img].
UTG calls $0.10, <font color="#666666">1 fold</font>, CO checks, <font color="#CC3333">Hero raises to $0.6</font>, <font color="#666666">2 folds</font>, UTG folds, CO calls $0.50.

Flop: ($1.45) 5[img]/images/graemlins/diamond.gif[/img], 3[img]/images/graemlins/diamond.gif[/img], K[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">CO bets $0.9</font>, Hero calls $0.90.

Turn: ($3.25) 2[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">CO bets $2</font>, Hero calls $2.

River: ($7.25) Q[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">CO bets $6.45 (All-In)</font>, Hero calls $6.45.

Final Pot: $20.15

When I first reviewed this hand, I didn't really understand why I was just calling the whole way. But do I raise when they're so unlikely to have me beat or let them keep firing? Do I need to raise because of the flush draw, etc.? I am getting myself into situations where I seem to have a very good idea of whether or not my hand is best, but then I don't know whether to let people who apparently want to just throw money at me continue to throw it and possibly draw or if I should just take the pot down right there/hope they decide to reraise and get it all with garbage (which they are far less inclined to do, it seems, calling induces bet-bet-bet a lot of the time for me while I am rarely reraised with garbage and usually take the pot down)?

Please consider the above hand without reads first. And then again with the read that your opponent has something like Q9 offsuit.

Any advice greatly appreciated.