For your first Lake Powell experience, I strongly recommend the south end of the lake at Wahweep. Much better facilities for new folks at the lake. Much more support for provisioning, mechanical difficulties. The Wahweep RV park is superb. Marina is excellent.
The only issue with Wahweep is that to get up lake, you may have to go around Antelope Point if the lake level is below 3620 feet. Not a real problem, just a rough ride if you go around Antelope Point because it is a narrow canyon and boat wakes will keep you rocking. Not unsafe, and for some folks like me, it is kinda fun. If the lake stays above 3620, then the Castle Rock Cut is passable and makes for a shorter more direct route up lake.
Launching from Bull Frog doesn't have the lake level issue, but, the RV campground is primitive with a limited number of full hook ups. The campground area at BF is very nice and is a distance from the RV park. Also, there is very poor provisioning at BF. It is just a more primitive place on the lake for people new to the lake. Those of us who frequent the lake will do both Bull Frog and Wahweep comfortably because of prior experience.
To miss the middle and north end of Lake Powell however, would be a mistake as they have their own different magic when on the lake. BUT, for a new person, start with the Wahweep end.
Just my two bits.