In my limited experiece, I have found with AA, its best to raise .5 of your stack, if a lot of people have called in front of you, typically if you get a lot of people calling in front of you more than likely there are pairs out there and someone else is calling with at least an ace which lowers your percentage of catching the third. Where as the other pairs on the board might not be that great but have a higher chance of winning. If it is just you and a couple others at the ring. Then limp in and see if you catch your ace, if you do slow play to try and let them catch a card to bet with, or if suits come out then you can raise big to chase out the flush draws. Just my opinion, but works well for me. Good luck in all your poker games
, unless your at my table.