Screw Disneyland! Lake Powell is the BEST-EST-EST! Powell has been my family's go-to summer vacation for decades, going to on 3rd generation. There's no place like it...
@txav8r is correct when he says you won't see the whole lake in 4 days... I've done 5-7 day trips for 30ish years and I know I've not seen it all. He's also right when he says it changes. Being a reservoir means one year your camping on a beach up the end of a canyon and the next year its under 20 ft of water. Or the water drops and you're staying on a beach a mile downstream from your last site because the water no longer reaches it. I've only camped in the same spot over again a handful of times over the years.
There are countless things to see. There's rock formations (including rainbow bridge), slot canyons, grottos, petroglyphs, Native American ruins, picturesque canyons, overlooks.
My advice to anyone is to just go with the intent to have fun. Plan to see a few sites, but don't overwhelm your schedule trying to see it all. Give yourself time to relax and play because after all... you'll be back next year.
You quickly learn that there are essentially 2 halves to The lake. Your style of camping may effect your choice in which region you choose to visit. The south end (Wahweap area) is known for wide expanses of water and large beaches. The north end (bullfrog area) is more of a small private beach up a canyon type region. There are exceptions to both in each area. Maybe its that I'm less familiar with theWahweap end? ...I've done both and that's just been my experience anyway. We've still ended up in fairly private spots even when staying in the south end.
A few times we've ventured from the north end to the south, from bullfrog to dangling rope to rainbow bridge and back... it's a pretty long journey.
You'll find that there are different ways of staying on the lake. There's the houseboat experience, the campground/rv experience, hotel experience, and the find a beach experience. Each method changes how you see and experience the lake.
My family has always gone the route of the packing the boat so full of gear you can barely get on plane and find your own private beach for a week experience. In fact, last year was the first time I'd ever stayed on a houseboat...
When staying up a canyon, you just need to make sure you're close enough to make the run back to the marina for fuel, ice, and ice cream.
The houseboat experience changes the game in the fact that you have less need to head back to the marina as often. Especially if the houseboat is equip with an accessory fuel tank. It's nice to have the shelter and convenience. The houseboat itself can act as a satellite station to launch extended exploration.
The campground experience pretty much positions you at the marina.
Navigating the lake is pretty simple if you have a map. The main channel is marked with numbered buoys the should correspond to most maps. The canyon entrances are also clearly marked with signs.
It's just awesome!
@Speedling it is worthy of being on your bucket list... I'd say, move it to the top of the list.
This comment ended up being way longer than I thought...