This is an all in one car rental place. The rental companies are on site with the cars parked right outside in their huge garage. The garage is connected to the center, so it's really close. The only thing separating it is a sliding glass door. It's air conditioned on the inside to keep you nice and cool. When you return the car, you park it back in the same garage. The different rental companies all have their own sections. This is a pretty good setup that they have going on.
The Rent-A-Car Center is bright and clean. I saw a Starbucks and some slot machines. Slot machines are everywhere in Vegas. I was not surprised to find them here.
My only complaint is that it's not within walking distance to McCarran International Airport. It's about three miles away. They offer free shuttles to and from the airport and the shuttles come frequently. You just need to be sure to allow yourself extra time to make it to the airport.