I travel to Palm Springs/Palm Desert area about once a month for work. Usually a 1-2 day trip. I almost always fly into Ontario as suggested by the previous post. As for public transit, I've seen the buses, but would recommend getting a rental car if you plan to get around very much. The heat can be pretty brutal this time of year, and additionally I am not sure on the running hours of the public transport as many services seem to shut down early in this area...(lots of retirees in the area). If you aren't planning on doing a whole lot of travelling in the area, the hotel/resort may have a shuttle you can use for nearby locations? Check that out as well.