No preferred height. But, I'll only go as high as I think I need to. Most successfull treestand we had growing up was only about 10' to the platform. The Cedartree Blind was in a pine tree with lots of limbs. Enough that we used the limbs as steps! One was well hidden and the height really gave all the visibility you were going to get. Dad killed 7 bucks in 7 years running with a bow on the day before gun season out of that stand.
