If you do make it to Yosemite and Sequoia National Park, then a RV is practically the best way to go and be able to stay inside the park boundry. There is only one lodge in Yosemite, and it is probably more expensive than renting the RV, and that in itself will be pretty expensive.
A alternate is to get hotels in the warmer valley area, and drive to the NP for day trips.
Either way, do not miss the "Grisley Giant" in Yosemite NP, it is 33' diameter. THe lowst tree branch is 105' above the ground. That branch is ovr 3' diameter too! You get there by taking highway 41 from Fresno to Yosemite's south entrance, then at the entrance station take a right turn, go about 2 moles south to the parking lot, and take a walk for about a mile. You will reach the trees, it is practically level walk. There is also a "Tunnel" tree, where you can walk through a opening cut into the base of the tree that is about 9 or 10' tall and around 3' wide.
Sequoia National Park has a campground at Hume Lake, you can stay in many cabins there. I think it is areasonable price. Being at 6,500' elevation, when I was there in July, 2009 it was not to warm. Take highway 180 into and out of the park, it is the most level route. Be sure to lock out overdrive on your car, or especially the RV if you rent one. This saves a lot of braking while going down the hills. And when going up hill, if you notice the transmission shifting frequently out of overdrive, it is much more effective to lock out overdrive, and stop the to frequent shifting that can overheat the transmission.
A family of 6 will fit nicely into many class C motorhomes. 7 is still small enough to fit on the somewhat tiny dinette and not get cramps from your neck being jammed into the corner at a angle.
Good luck on whatever you decide.
You might want to spend a couple nights at Hume Lake, visit the area, and then take 180 west toward Yosemite, filling with gas in Sanger, shipping gas into the foothills is really expensive, while there is a pipeline from the refineries to Fresno, Bakersfield, and other valley towns.
Then once in Yosemite, check out the Grisley Tree, and then the valley. You can spend the rest of the day there, and go towards Merced that night for any local hotel you can find. The next morning, enjoy the pool if you like, or head towards Lake Tahoe via 99 to Sacrometo, then highway 50, it is a good drive. There are several hotels and casino's in that area. Many places to stop along the shoreline and enjoy a picknic. I like to get a couple Subway sandwiches for such a picknic.
Lake Tahoe will be cool as well, the lake probably about 55F because it is basically snow melt, and the local weather fairly cool as well. Finding a hotel might be difficult, so check ahead. Carson City has plenty of rooms, and unless a huge event is going on 90 miles away is Reno, with a huge number of rooms.
So instead of renting a RV for several hundred dollars, and paying $0.25 to $0.50 per mile to drive it and even more for gas (at 8 MPG, you will pay about $0.50 for the gas alone) you might not find such a long trip cost effective. Unless you are planning on buying a RV soon.
You can google map the various routes, and find the distances. This will give you a general idea of how expensive the trip might be.
Also be sure to check
Weather.com for the local weather up in the mountains. It can get really cool at night at 6,500' elevation, even while it is over 105F in the day in Fresno and Merced.
Be especially careful to apply sunscreen at the higher altitudes. You can burn twice as fast, with little dust in the air, and closer to the sun.
Fred.
