Early in my young poker career, I had pocket AA in a cash game. A player raised pre flop and I then re raised as I was supposed to do. He called and we saw the flop. He immediatel went all in. Notknowing this player and how he plays, I eventually layed down my AA thinking that maybe he had a set a Q's as a Q came on the flop. Turns out he had nothing and I lost what should have been a no brainer. Found out later he was just a reckless player. After playing many hours of poker I realized that most players that do an all in after the fact are ususally trying to bluff.
By the end of the night I had made up that pot that should have been mine and then another 250.00. Same player, different results. I flopped a boat and and then checked to him after pre flopped raises. I had 7 6 suited. Flop came 7 6 6. He raised all in. I called and he was done for the night.

So to lay down AA in a tourny, yes, depending on the nature of the table and where you are in chip standing and how far off from winning. AA in a cash game pre flop. Headsup , never again. : )