I know the handcuff knot just in case I have to rescue somebody. 
I see you've updated your initial post to include a body harness scenario. One thing that troubles me about using two loops for a body harness is that in a vertical lift there is little to keep the loop for the legs from riding up.
If you want to emulate a certain type of harness, such as:

...it seems like you'd want three loops, as seen in a triple bowline:
http://notableknotindex.webs.com/triplebowline.htmlI'd suggest carefully suspending yourself with these two approaches, and see which one you prefer. Keep in mind that a theoretical victim may or may not be conscious.