Vegas has a lot of hotels to choose from, and pretty much all of them have pools. So why the Mirage? Well their pool is great. It's also close to the dolphin exhibit, so it's like you're sharing the same water, except you aren't.
The Mirage Pool has a large area for laying out, a bar area, a few water falls and tons of chairs. They also have pool side service and extra large Mojitos (like 64 oz, seriously). If you're traveling with little ones -- have no fear. Mirage Pool comes staffed with life guards.
The water temp was just right, and it wasn't too crowded.