We've taken 101. Ancient Redwoods RV at Redcrest is a nice stop right in the heart of the big trees. It's big-rig friendly. There are some lovely trails nearby of all abilities to just stroll through the trees. It's a beautiful area.
If you want to tour San Francisco we stay north of the bay at Sonoma County Fairgrounds in Santa Rosa - wine country. It's just a gravel lot but has shade and takes Good Sam and other cards. You have to make sure nothing else is going on at the grounds. Park the car and head south and take the scenic ferry from Larkspur into San Francisco. It passes by Alcatraz to the Ferry Building near Fisherman's Wharf. We had pre-arranged a small van tour of the city for the day and it was a great way to see all the highlights of the city with stops to get out and explore. We had about 1-1/2 hr. at the Japanese Garden area and lunch in Sausalito by crossing the Golden Gate Bridge.
Leaving the area we continued south on 101 to Novato and picked up 37 east to I-80. You can pick up Hwy 50 out of Sacramento for a long, very doable uphill to the Lake Tahoe area. At Echo Lake pick up 89 a very short distance to 88 at Woodfords to 395.
From there are many ways to get to Las Vegas. We've done 120 east at Lee Vining to Nevada Hwy 6 to Tonopah (a very nice rest area to spend a night) and pick up Hwy 95 south into Las Vegas.