I agree with minivans over SUVs as rentals. But if you go through any mainstream rental agency you will have a geed enough vehicle. It won’t be what you would buy for long term use, but it will be relatively new and should be functional. If you look at prices on US website then all of the insurance costs will not be included. Insurance can double the costs.
If you are more nature folks than city folks then LA to SF to Yosemite to LV (via Death Valley) is a good way to spend a week and a half. Just a note that right now the road that connects the west side of Yosemite to the east side is closed for winter so Google Maps will not show that routing. But using route 120, it takes a little over two hours to go from Yosemite Valley to Mammoth Lakes in the summer.