i don't think you should lay down either hand. but it really depends how well you know your opponent. if you play loads and loads and loads with an opponent and know that the only possible hand he could have is AA then you need to fold. but i don't think you can fold in any other cases.

in the first case you're odds are too good. there's 150 in the pot and you need to call 70 (you know you're both going allin). that's 2 to 1. no way you can fold KK to those odds.

in the second hand, because your opponent made such a big bet - i think there is no way you can fold. a hand like QQ, AK or JJ/TT make that bet to try and make players fold. doesn't he want to keep you in the hand when he has AA? most players do. so again, no way you can fold IMO