Got our 3 day rental via Priceline and no complaints. Got a midsized car which = brand new corolla (Avis gave us a Dodge Avenger in this category in LA), but it came with the GPS included (already had my own), and pickup/drop off from LAS was a breeze. Would do it again.
TIP: we chose the DIY refuel option and there are tons of gas stations around so refuel yourself--it's way cheaper and simpler.
They did try to pressure me to buy extra insurance AFTER I told them I had extra on my Mastercard, and I didn't care for the fear tactic they used on me (they say you have to pay upfront for any thing, your fault or not),.