TIP: use their free wifi here (very spotty though)
i only fly southwest here at McCarran, and the layout is very disjointed. I can't say for other airlines but southwest has two areas with available gates. So if you went to the wrong gate (or wanted to visit a friend from the other gate) , and that gate happens to be on the side, you have to pretty much run to the other side of the airport. Also, the rental car center have to be shuttled (wastes time). There is also one rental car company that is not even in the rental center (i think it's fox). Do not rent from them!! they are far away, which is a waste of time. Rentals in LV are cheap anyways.