[slowhand5]

I'm really not a big fan of raising aces in early pos in a 6-max game and I think to do it in a full handed game is really pretty sucidal. I would only do it if you had a monster aces hand like A-A-J-10 double suited or similar and obvisouly with 3 calls from behind this is a decently loose game. Unless youve really shown a wide raising range to these guys its likely they've put you on aces (whether thats smart or not). If you miss you open your self up to getting raised by two pair or the draw and even if you hit the ace the action might dry up.

In this case you hit your ace and the other guy hit a big draw. I disagree with stefluv that a check-raise on this flop is your best play. In fact I think that would be your worse possible play at this point. If he has a set he'll re-raise you and the money gets in anyway. If you check-raise when he bets his set on the flop you give him the small chance of making the hero fold b/c its possible to put you on a set of aces here (pfr, with massive check raise on flop). If he just has two pair he might meekly call you down which is just fine, you really dont want to raise him off that hand. I also doubt that he really makes a bet on the flop with a small draw with 3 to act in front of him. He might make it there with the 17 outer but do you really want to try and get all your money in on the flop against a hand thats only a slight dog? Bet the pot on the flop.

Check raising the turn? Might work but more often than not just keep betting. He could be paying you off with a set or two pair and you make him pay full price on weak draw like the open ended straight.

You got unlucky here but I really dont see a better way to play it. The pre-flop raise with aces is debatable but it worked out great for you when you hit your ace. Keeping it simple is the way to go in omaha, fancy check raises will just get you in trouble.