McCarran International Airport
About five miles south of downtown, this airport has flights from all over the US and the world.
The Downtown area is rather compact, so a rental car isn’t needed because traffic is bad. However, you may want to rent a car if you plan a day trip to the Hoover Dam, Grand Canyon, Area 51, or petroglyph sites.
The RTC (Regional Transportation Company) provides local bus service to Downtown, The Strip, and the airport. Taxi cabs and Uber are widely available.
The RTC provides a free(!) Downtown Loop service that hits many of the hot spots. Note that service ends at 8:30 M-Th, midnight F-Sa, and 7:00 on Sunday.