We booked a high school group at the BW McCarran Inn and received a great rate ($67/room). When we first walked in I saw a lot of teenagers in the lobby and hallways and thought, "great- we're not going to get any sleep for the next two nights". Boy, was I wrong. We were on the bottom floor but we heard nothing at night. No stomping overhead and no noise from the neighboring rooms. The walls are obviously well insulated. The staff was courteous and helpful. The breakfast was good- pastries and muffins (storebought), cold cereals, coffee and hot water for tea, oatmeal, or hot chocolate, bagels, french toast and waffles for the toaster, juices, chocolate milk, and milk. The breakfast area was kept clean and well-stocked.
We didn't use the pool but other guests seemed to be having a fun time in it. I didn't see a fitness center on the hotel map.
Be aware that Las Vegas has TERRIBLE tasting water. We bought a gallon of bottled water and drank it during our stay because the tap water is so nasty. This is not a hotel problem, but a city-wide problem.
This is not a fancy hotel, but it is comfortable, clean, and provided a great stay. I will definitely stay here again when visiting Las Vegas.