1. Antelope Marina is pretty bomb diggity as Josh said.
Mini two-way cable park in the marina
great cart service for hauling peeps and goods up and down the ramp (lake is a little low so its a long haul)
simply put it is the newest marina on the lake
*speaking of the lake being low. IF the snow pack that feeds the lake takes a dive like it did last year the run-off will be piddly again, which means the castle-rock cut will be dry. if this happens Antelope is a NO-brainer as it will save you over about an hour or more of time being beat-up in your boat as you traffic the long way around antelope (landlocked)island
2. Wahweap is the other marina to choose (without driving deeper into utah)
there is a camp ground there for RVs and such that is right next to state-line launch ramp.
3. Lone-rock for parties as said
Places to see on the lake: can't really go wrong with any place on Powell. Padre Bay is huge with other smaller bays and canyons. Also there is great history there. The crossing of the fathers that explored the are came through there back in the 1700's thus the name.
Rainbow bridge, antelope canyon, and navajo canyon are the places that the tours go. just fyi if you want to avoid it, see what most see, or even find big tour boat waves to sling a tube into ** careful**