Most of the time you only get one card on each Ace after you split. It's obviously better if you can find a place that allows you to hit them after you split, but it's much more common for them not to allow you to do that.
I would say the couple of casinos i have played at you only get one card on A's. I would say this is far more common than allowing you to hit afterwards. If you could that would be an advange to you (the player). You could split A's and then double down afterwards?? That would be great.