-- Last Updated: Apr-14-13 12:46 PM EST --
Make sure water levels are high enough you aren't paddling in algae mats. We saw Hite from a distance on our first visit and it looked like a solid sheet of bright glowing green. We decided to start our southward trip from near Bullfrog that time. That was a drought year, in October. Check to find out what you're likely to encounter.
Moki Canyon is a beautful day trip. I say day trip because it IS sheer, high, vertical rock walls, very narrow for much of it. Jet skis and powerboats can make for some wild rocking and rolling in there, but it's worth paddling anyway, as long as you don't freak out over those kinds of things.
Get the Fish-N-Map pair of maps for Lake Powell. While they are quirky for sure (don't trust the compass rose on them!) and have limited info about land features, they do note floating toilets, mile marker buoy locations, water depths, and some topographic features. Supplement with a good hiking-oriented map for more complete information.
Bone up on the invasive water species boat inspection requirements, too.