Both my kids went to the Schlessman YMCA at Colo Blvd and Yale and we loved it. The staff are great, and they stay and stay - there are still some staff there from when my daughter was there and my daughter is 12 1/2 now! Everyone is well-trained, the facility is great and the program is very well-organized. The ECE program for 4 yr olds is coordinated with Denver Public Schools as well. I recommend it very highly.
take care, S.