KK Flops Everything But in Multiway Pot

Bet it. Sure people play a lot of Aces, but you can't just assume someone has one and even if the A is out you can still get the turn checked to you if someone as Awk. Your hand might be the best and you want to buy the button so you can get a free card on the turn to draw to your 5 outer. If everyone checks the turn, I'd check behind and call a river bet.