Just to add to this, I called this morning to book a one for Monday, first week of September, and I was told to check in at the Oasis Bar & Grill 15 minutes prior to the reservation. I don't know how strict they are about that, but I'll probably do it just to be sure they don't give it away. He said half a day is 4 hours, so ours will be from 10am - 2pm. The price was only $31. I think that's really reasonable to know you have a reserved comfortable shady spot for 4 hours, no worrying whether you'll find open chairs or whether someone will snag them if you walk away.