What is a good height for a tree stand when bow hunting?

It all depends on the terrain and the available trees in the area.  When it comes to bowhunting, it's all about being in the right spot to get you close enough for a shot.  If that means the only tree available will only let you get 6 feet off the ground, you have to work with what you've got.  When given the choice, I like my stands between 16 and 20 feet.