I have AKo on the button and the flop came King high all spades. Checked to me and I bet the pot figuring I had to identify any made flush and make a flush draw pay. Here is the hand.

Ultimate Bet No-Limit Hold'em, $.25 BB (9 handed)

SB ($13.75)
BB ($23)
UTG ($24.50)
UTG+1 ($20.80)
MP1 ($21.55)
MP2 ($10)
MP3 ($24.75)
CO (Villian) ($50.30)
Hero ($27.25)

Preflop: Hero is Button with , .
UTG folds, UTG+1 folds, MP1 calls $0.25, MP2 calls $0.25, MP3 folds, CO (Villian) calls $0.25, Hero raises to $1.5, SB folds, BB folds, MP1 calls $1.25, MP2 folds, CO (Villian) calls $1.25.

Flop: ($5.10) , , (3 players)
MP1 checks, Villian checks, Hero bets $5.1, MP1 folds, Villian calls $5.10.

Turn: ($15.30) (2 players)
Villian checks, Hero checks.

River: ($15.30) (2 players)
Villian bets $10, Hero folds.

Final Pot: $25.30

Results in white below:
Villian doesn't show.
Outcome: Villian wins $25.30.

Should I have bet out again on the turn? Villian had us all covered by double and had been playing pretty solid, straight forward poker. Nothing wild. My read was that he had the made flush and was slow playing it.

What do you guys think I could have done differently?

I don't understand your check on the turn. You thought you were ahead on the flop, you bet the pot and got cold called. I think that you would be better off making your opponents $10 river bet (2/3 the pot) on the turn when he checked to you. An 8[c] probably didn't help him any. You definitely have to fold on the river.

I agree. Bet $10 and see what he does. If he's drawing to the flush, he will likely lay it down now that the board pairs. If not, you may get a free showdown.

I dont mind the check at turn turn as long as youre going to call a river bet (not now that a 4th spade hit though)

Obviously he was only drawing to the flush and had a smaller pair than you did, most likely AspQx.
Why check the turn and give him a free chance to beat u? If you bet out 8-10 there, then you would really find out if he has the flush or not, if he had it he would have definitely raised.

In this case though, even if he didnt have the flush, the 4th spade came and it turned out either to be a good opportunity to make a good value bet if he had the flush, or bluff you out of the pot if you didn't have a high spade.

What do people here think about leading out against the 4th spade on the river if you don't hold one? I find that a lot of the time, people will fold a 9sp or even 10sp, depending on what the board looks like.