10 - 12 feet if you are an alcoholic.

I truly have difficulty understanding why questions like this are asked. You need to put it at a height that is convenient for you. Or if it is a piece of furniture, get one that looks good to you and again, is convenient.

If I went into a donut shop, I would not ask anyone which is the proper donut to buy. I would purchase one that pleases me. 

It may be nothing more that a rumor, but I think that Emily Post is dead.

JayR