If you're renting in LAS (McCarran Airport in Las Vegas) I highly recommend Thrifty or Dollar. They are the same company but operate separately. Their rates and vehicles are mostly identical. I have always rented from them (and Hertz, occasionally) and never had a problem and I have always gotten great rates.
I once considered renting from Payless, a "no-name" kind of like Fox, but after talking to several people I heard horror stories. I one time got a great, low, low rate from a "no-name" in New Orleans and they tried to charge me $250 extra when I returned the car for a scratch on the fender. I had the damage sheet from when I picked up the car which indicated a scratch on that fender, but they argued with me saying this was a new scratch! It was a load of nonsense, but then I thought of the ramifications - had they not backed down, and charged my card (remember, I don't have a lot of time to argue as I'm rushing off to the airport), it would have been a pain in the neck to go after them for this wrongful charge. Even if I got the $250 removed through my card company it wouldn't have alleviated the stress I went through. Most likely I'd have had to have taken them to small claims court, THERE, in Metarie, LA.
After hearing similar stories about other "no-name" agencies, I am loathe to trust any of them. I stick with any national, "big-name" agency, now. It's worth the little extra, to me. I heard a big one they're going after now is claiming that they smell smoke in a car even when the renter is a non-smoker and didn't smoke in it. Who wants to deal with that? Definitely stick with the bigger name agencies, is my advice.
Also, both Dollar and Thrifty let you sign up for their "express" cards, which let you set up a profile online and then skip the line at the rental counter. It's similar to Hertz's #1 club Gold, if you're familiar with that, but unlike Hertz there is no fee - it's free. I used to wait in line for up to 1/2 hour when I would fly into LAS, but now I have the cards so I have no wait time, I go right out to my car.
Try expedia.com to compare rates from all the rental agencies; you'll find Dollar and Thrifty will probably be the lowest. Another nice thing with both of them is that their websites will let you see the FULL price of the rental, breaking down the base rate and ALL taxes and fees so you can see the full total, which is usually a good 25%+ more than the base rate (that's true for all agencies).
Good luck - your vacation should be fun, Nevada and Utah are absolutely BEAUTIFUL!
EDITED TO ADD: Don't completely rule out Fox - I'm just saying that unless you hear some good stuff about them in researching them you shouldn't use them. But if you can find some positive reviews of them then give them a try, especially if it will save you money.
Use travel review websites like TripAdvisor (my favorite) for more details and more traveler reviews. Also yelp.com is good for reviews. Here is a link to a yelp review of Fox:
http://www.yelp.com/biz/fox-rent-a-c...arch/query:fox car rental
Doesn't look too promising but keep researching, try to find the latest reviews that you can find and you'll have a better idea.
Good luck!
