When do you fold AA?

First hand I like calling the all in. Your opponent could have AQ or QK. If he flopped the nuts Q full of 3s he would not play the flop so fast, he would slowplay.

Second hand, it seems like your opponent really likes his hand so I would go all in preflop after he reraises you. Don't get fancy with the Aces, after all, they are only one pair.