I’ve looked up hostels, camping, and hotel/motels w/ the discount websites. Any other ideas?

We are planning to travel around California and Nevada in April this year. We are flying to Los Angeles from the UK and then hiring one vehicle from there, travelling around for 3 weeks and returning to LA to fly back. We will be doing a mixture of camping (in our own tents) and staying in hotels. The group consists of 3 adults, 3 children and 1 two year old. We cannot decide between an 8 seater or a 12 seater minivan (hire vehicle). The websites suggest that an 8 seater may have room enough for all of us plus luggage plus 2 tents. There seem to be no decent illustrations of what the 8 seater and 12 seaters can carry. Does anyone know how much capacity 8 or 12 seaters have and what would you recommend for our party?

I’m not going to live in hotels but like camping and B&B’s, renting. Any idea at all?