I would agree with this post, Basecampervans is a great company, their vans run on Compressed Natural Gas (CNG), as well as regular gas just in case you are unable to find a CNG fill-up station (btw there are tons of apps for smartphone that will help you find a CNG fill up location). CNG is great because its better for the economy, and it will cost you less money than gas for your trip. Also the couple (Matt and Jenn) that run Basecamper are so nice and accommodating, they will help you with your trip planning (they know all the good spots) through out the west, will recommend places to go based on your interests. If you don't have cooking equipment, sleeping bags, bike racks, etc, they are able to provide all of those additional amenities for you as well.
In terms of the setup of the vans, a bed setup with clean sheets is available. There is a solar panel on the roof, linked to a battery inside that can store your power, so in the summer if its hot, you can run fans, charge equipment, phone, or in the winter run a heater. I rented a van for a trip to telluride over the summer and I had a dog with me, so when I went on an adventure and was unable to bring my dog, I was able to leave him comfortably in the van, and run the fan so he would not overheat.
The van has an amazing setup and Matt provides great customer service (he knows so much about the area---climbing,sking, mountain biking, ice climbing), I would definitely rent a Basecampervan on my next long adventure.