I stumbled into this Starbucks location one morning (ok one almost afternoon; it was a little after 11:00am) hungover from the previous night and needing to get something in my belly. There are two Starbucks located on the main floor in the Luxor Hotel and Casino, and this one is located by the West Tower Elevators.
It wasn't busy at all when I went, and I found the service to be good. I picked up some yogurt meets granola thing from their refrigerated case that I thought my stomach could hold down, and ordered a Grande Iced Peach Green Tea which I thought would help replenish my fluids without dehydrating me with all the caffeine.
The tea was good, but could have used a little more peach flavor. The yogurt was OK, I thought the granola and strawberry flavors were tasty, but the majority of the yogurt was plain unsweetened Greek yogurt and didn't taste very good by itself.
There are a few tables inside and a few outside the Starbucks (but still inside the casino) so I sat outside and people watched while I relaxed. Prices may have been slightly higher than back at home, but nothing I noticed.