Northern California in late May

I would take the 99 to South Yosemite, I like KOA Maraposa/Yosemite as a basecamp. Then continue up the 99 with a stop at the wineries at Lodi, The Jackson Ranchero RV park casino is lovely and central. Then take the 50 to Reno, come back on the 80 all the way to the 101. Then up the 101 through the Redwoods, Benbow KOA in Garberville is excellent and the restaurant at the Benbow Inn is wonderful. Lots to do and see with lots of choices of routes. Enjoy.

Snowman, in Virginia City...the graveyard...and in Northern California the Avenue of the Giants. We welcome you to California!

With knowing what I know in this area, if I was going from Las Vegas to Crescent city with a stop in Reno and Yosemite, I would go to Reno, then come around to the west entrance to Yosemite. Then I would get over to I-5 and take 20 over to 101 and up the coast. Many places that cater to RV's.

With all the snow this year Tioga Rd. In Yosemite will most likely be opening later than usual, perhaps June. Check the Yosemite website for updates. If possible, avoid the Valley on weekends.
Since you aren't into hiking I'll defer to others as far as how long to stay there. Have a great trip!

In the Carson City area, Virginia City is fun, at least for a day trip. Ive never camped there.

If you like the eastern slope of the sierras, I like Eagle Lake, which is north of Susanville on road 139. There is dispersion camping, but the RV park in Spaulding is a nice little park with great service and clean facilities.

Along the coast, Mendocino is real nice. We like Pomo RV park.

Have a great trip.

Lassen National Park. The coastal redwoods south of Crescent City.