The problem with that many people in a van is that there isn't room for luggage for everyone. You mi

They plan to rent a car in Las Vegas and drive to Zion and Bryce in Utah. They will return the car to LV. They are 2 families - 4 adults and 4 children. I have checked several car rental companies and the van they all offer seats up to 7 people. Does anyone know of a dependable rental car company in Las Vegas which rents vans for 8 people (driver + 7 passengers) ??
The problem car hertz rental sales with that many people in a van is that there isn't room for luggage for everyone. You might be better off renting two vehicles and if you don't have cell phones you can buy them here for under $20 at places like Wallmart to keep in touch. This also lets you switch kids periodically if the kids get antsy.
If the smallest is 10, comfort is going to be an issue unless they rent a full sized van rather than a mini-van - even if it were just 7 people in a 7 passenger van. Think of it the same way as you think of the middle person in the back seat of a compact car like a Toyota - just because there are 3 seatbelts does not make it comfortable for that middle person.
Snd even with minimal luggage, most mini vans do not provide space for even 6 small overnight bags - really, there is not much space in the back. Many people who purchase them get a "stretch" car hertz rental sales model with a few extra feet for that reason, but I have rarely seen these at rental places.
My recommendation is to rent 2 mid sized cars for about $40/day. More if you add insurance. I like to use www.orbitz.com for rental car comparison shopping, then book directly with the rental car co website.
I agree that two cars is a much better answer. the problem is that the OP said the renters are from outside the US or the mandatory insurance can really raise the rates. car hertz rental sales I suggest they rent in advance in the home country - but be sure the cost includes taxes AND insurance.