This is Vegas, all hotels hold luggage for guest prior arrivals and after departures, nothing new. What I ussually do is see how late a check out I can get, have the hotel hold my luggage, check out, relax by the pool, walk around a bit and catch some of the free shows, have lunch/dinner. Eventually around 7 or so, I'm pretty much done, change cloth and head to the airport. After check in, security and all that, I have about 3hrs or so to spend waiting for my flight. You do not mention if you can SDC for an earlier flight, not sure if that's an option for you or not.