depends on the situation, settings, and cover. for me, 90% of the time i will end up 18-22 ft.....here in missouri thats about the hight of where most trees begin to fork. down there in the pines you could go 60ft, but that wont do any good. i don't like to go under 18 unless i have some cover around me.
I'm usually around 20ft + up the tree....however, it will depend on the terrain, where your hunting and where you got good shots.......If your too high you may not be able to get off a good shot, if your too low those wise whitetails might see you before you draw.....so gotta get out there an experiment a little! good luck!
If you're lucky enough to be on private land and can leave your stand up during the off season you can tie an old piece of cloth or something of the sort to your stand. I like to use an old camo bandana that I have. That way the deer get used to the movement and eventually don't bother even looking up when there is slight movement. This may just give you the time to draw your bow or raise your gun without being detected.