[Ghazban]

I raise so much other cheese that there's no reason for me to ever limp AA and KK. However, limping with the intention of raising is good if all the following conditions are met:

1) There is a very good chance somebody behind you will raise (a couple action players raising every hand, for example)
2) Your limp/reraise will be large enough to pot-commit yourself, thereby making postflop play trivially easy. The limp/reraise defines your hand so clearly that you can't afford to give somebody good implied odds to outflop you. If they take bad odds and outflop you anyway, that's just poker.

Limp/calling AA/KK is never a good idea unless the raise you are calling is large enough to pot commit you (which should rarely be the case unless you or the raiser are extremely short stacked).