Listen to RCook - he's THE expert on Lake Powell. I've been to Powell with him and several times without him.
Here's how I went to Lake Powell with my houseboat...just scroll down to see the pictures.
One More Time Around: Houseboat - 2,000 Miles to Lake Powell
And how I went back.
One More Time Around: Big Duck Goes Back to Lake Powell 2015
I've used about 200 different ramps from Alaska to Key West and so far, no inland body of water compares to Lake Powell for beauty, diversity (and afternoon tempests). This includes Lakes Kentucky, Barkley, Cumberland, Havasu, Shasta, Whiskeytown or even the Great Lakes. We especially appreciated the No Bugs or dangerous water creatures on Powell, which is seldom the case for much of our other cruising.
Something to consider is what you plan on doing on the water. From my perspective, Powell is best for folks who plan to beach or anchor nights, enjoy being on the move and prefer remote untouched scenery. If you want to tie up overnight or for dinner and your cruising will be limited, then a smaller lake with marinas and restaurants might be a better choice. There are only a few marinas on Powell, one of which is accessible only by water. While we were at "Dangling Rope" on Powell, a houseboat pulled in for fuel - we heard the skipper tell the dockhand, "Stop the pump at 1,000 dollars."
I can't give you recommendations on the number of boats you’ll want, but my houseboat is 28’ x 8' and we had 4 adults, 2 kids and a dog on board for a week with all nights on the water – and wouldn't have it any other way.