Ax is something that I play a lot of shorthanded, but in a full ring game, it doesn't have as big of a place in my game. In shorthanded play I would raise with it, and depending on the circumstance be comfortable with making a pair. Calling with Ax shorthanded can get you in trouble sometimes when your opponent raises with a higher A.
In a full ring game, opening up with Ax is fine at the cut off or after. Now if Ax is suited, I would really like to get in on multiway pots with great pots
odds with the hopes of making a nut flush and taking in a big pot. I would also be more inclined to open up with suited Ax from around the lojack seat or better.
The main thing with Ax is that depending on the situation, you pair of Aces with the weak kicker could be useless, and even if you make your 2 pair, that can be useless as well if your opponent has a better 2 pair, or the board pairs, and you are out kicked again!