All the major Strip resorts are served by both Uber and Lyft, but there's a designated ride-sharing pickup/drop-off area, and it's generally not near the taxi stand. Just ask a hotel employee if you can't spot it. There also are designated pickup/drop-off locations at large events, such as the Electric Daisy Carnival and Life Is Beautiful festival, and event spaces such as T-Mobile Arena. Be aware that rates can fluctuate rapidly, especially in the cases of holidays and special events, when surge pricing may be in effect. And surge pricing can happen almost anytime on the weekends or during large conventions. Anecdotal evidence suggests that pick-up time estimates aren't always reliable in Las Vegas because of traffic and lights.
After some rough spots in the early days of serving Las Vegas, the process of using both Uber and Lyft has become much smoother. Uber Pool, X, XL and Select are available, along with Lyft Line, Lyft, Plus and Premier. Both services also are allowed to pick up and drop off passengers at McCarran Airport. Sometimes customers may even receive autonomous vehicles (with human monitors).