During my recent Vegas trip, I also visited Luxor Spa. It is modern and clean, but I wouldn't call it luxurious. They need to turn off about half the lights - it is too brightly lit. There are two hot pools plus a cold plunge pool. The pools are on the small side. The dry sauna and steam room are huge.
I saw only one other guy while I was there, and he kept his towel tightly wrapped the entire time. I can't really recommend Luxor Spa. Perhaps Luxor Spa might be worthwhile if you happen to be there on a Sunday, because there is a Sunday pool party that is gay-friendly.
I understand that Luxor Spa used to be THE PLACE for action back in the day. It was very busy, open 24x7, and basically operated like a gay bathhouse. When MGM Resorts acquired the property, they made changes to discourage inappropriate activity (such as changing the hours and even bringing in security). As a result, Luxor Spa is basically deserted now. I don't know how this makes business sense for MGM, but whatever.