Y.Y.
There are two great pools more south of Denver. One is at the Lone Tree recreation center. It is zero feet entry, with water feature. It gradually turns deeper into a 1 ft, 2ft, 3ft and then goes into the rest of the pool. They allow floaties. It is in-door, so great for winter swims.
The other pool is at Goodson Recreation Center. University & Araphoe They have a toddler pool with a great slide. Floaties are also allowed. Again it is indoors.
Both are pretty inexpensive.
Best of luck! :)