There's enough to keep you occupied for at least 3 or 4 days! We spent a week there.
We stayed at Diamond Lake RV Park, just north of Crater Lake. That's the closest rv park to Crater Lake.
Besides doing a day trip on the road all the way around the lake, stopping at all the sightseeing stops, don't miss the absolutely gorgeous drive along the North Umpqua river. It has a "scenic road" name that I can't recall at the moment.
If you are into short hikes of relative ease, there are several that end at some spectacular waterfalls, especially on the north leg along the North Umpqua. There are maps available for this scenic byway showing all the places to stop.
Then, after that, there's the south leg of that same scenic drive, this one along the Rogue River. We found the north leg, along the North Umpqua, to be the more spectacular of the two but both are worth seeing.
If you'd like to get some idea, check out Vicki's "postcards" at
http://vickiandsteve.com . Click on "2010 postcards" and scroll down and look at the postcards for July 12 and July 15. That covers the northern leg of the scenic drive, along the North Umpqua river. We did this segment in June 2010.
Then click on Home, then 2011 Postcards, then look at the postcards from July 8 through July 24. We were there in about early September 2010 for a week to see Crater Lake and the southern leg of the scenic drive. We did the nothern leg along the North Umpqua earlier in the year, starting from Canyonville when with a bunch of moc'ers at Seven Feathers.
It's a beautiful area. I hope you enjoy it. The color of the water in Crater Lake is beyond description. Gorgeous.