Hand 1: Betting sucks since you are building a big pot OOP vs. two opponents without a strong hand. So i check, with the intention of folding to any bet.

Hand 2: Since you didn't get raised on the turn i doubt villain is holding 9-x. Villain has either a full house or a busted flush draw, and given the fact that this river is a good card to bluff i would call anything but an overbet on this river.