Definately go to Bullfrog. The ramp is a little sketchy but once your in your fine. Launching at Wahweap is OK but then you have to go through the Narrows. They have added more no wake areas which is good for houseboaters towing boats, cause the Tour Boats Screw everything up, but it also slows down non house boaters. I read that they have averaged 1 boat sinking everyday this summer all in the Narrows, Primarily form the wakes of the Tour Boats, and 1 week they had 13 ski boats submerge.
I am off to Powell tomorrow for 2 weeks and then back again last week of the month.
Have Fun and Be safe.
here is a good website to check out. http://www.nps.gov/glca/