All of the action is on the lower level. Head straight back to the escalators and go down. There you'll find JPRA, and The Mummy along with a few shows. Here's my USH page. http://www.nogodforme.com/USH2005.htm
The top level has BTTF (don't ride it, simulators make some people sick), T2, Shrek, The Back Lot tour, and Water World is at the front right as you walk in.
The USH page has a map, try this. http://themeparks.universalstudios.com/hollywood/website/vi_interactivemap.html