At $25 NL you should just camp for monsters, and A-x almost never becomes a monster, and when it does, it's hard to get any action unless you're lucky enough to be up against a smaller flush.

At $100 and $200 NL, I sometimes like to raise these hands and bet any flop, which I think is favorable to trying to limp in and flop something. If I do happen to flop a flush draw, then my hand will be fairly well disguised if I hit my flush, and I'll win more since I've been building the pot. If an ace flops, than it's likely I'm the only player with top pair, but if I'm getting action I'll usually slow down.

Plus, since I have an ace in my hand, it's slightly less likely my opponents have playable starting hands, and so I'm more likely to just win the blinds.