marginal hand how much to bet on river?

[108suited]

The game is Party Poker's 10/20NL. I open in the cutoff with Qd Jc for 60. The button calls and the bb calls.
Me 3.5 k - Good lag but I've been playing "slow" or more solid the last hour.
Button 2k - Solid
BB - 1k Unknown

Flop is Qh, 5s, 8c. It's checked to me and I bet 150. The button calls and the BB folds. Turn 3h. I check and the button checks behind. River 6d.

1. How much (or what range) do you guys like to bet here with this "marginal" hand on the river?
2. How does this change, (if any), in this example if the hand were KK or AQ? What about QQ for top set?
3. Anybody like a turn bet? The turn play check seems standard. Other lines on this "simple", but often encountered, type, marginal hand?



Thanks for your help