Crater lake is cool but 3 nights might be a little long. As said above, I would head east. Fort Rock and Hole in the ground are cool, Crack in the Ground has 14 trad/toprope routes, Silver Lake has the "Cowboy Dinner Tree" (reservations required) very recommended if you like meat. Summer Lake has hot springs, Hart mountain Antelope Refuge is awesome. My wife and I hit all these places on July 4th weekend. Wanted to go to the Steens and Alvord desert but ran out of time. Lots of gravel roads but worth every mile. BTW the lakes in the Hart mtn area are on a 10 year wet dry/cycle and its on the wet cycle now and is incredible.
Just suggestions. Good luck.