Harry Reid International Airport (LAS) sits literally on the south end of the Strip — a ten-minute taxi or rideshare to Mandalay Bay and not much longer to central Strip resorts. It is one of the busiest U.S. airports by passenger count, and the Strip-facing terminals were deliberately oriented so passengers can see the casino lights on landing. Domestic flights connect to every major U.S. city; international service runs to Mexico, Canada, the U.K., and a growing list of European and Asian gateways.
Driving from Los Angeles takes four to five hours via I-15 — a straightforward but visually unrewarding cross-desert drive. Friday evenings going out from LA and Sunday afternoons returning are brutal traffic. From Phoenix it is about five hours, from Salt Lake City around six. There is no useful passenger rail service. Greyhound buses connect from LA, but flights are usually cheaper for the time.
Resorts World, the Tropicana, and the southern Strip resorts are the closest to the airport. Downtown is a 15-minute drive in good traffic. Don't accept rideshare prices on big event weekends without checking — surge pricing on Sunday evenings during conferences or fight nights can be punitive.