RE: How high do you climb?
High enough that I feel I can get a clean shot(within my abilities)while blending myself and treestand into the limbs and foliage of the tree.
My first deer with a bow was shot from a treestand that was only a 10ft ladderstand. The cover was perfect at that height and the deer was shot @ 5yds away from the base of the tree.
I dont think the actual height of the treestand is the determining factor but how well you and your treestand become a natural part of the scenery.
The only thing that a lower height treestand means is that you'll have to restrict your movements to the absolute minimum.