I wrote to a friend of mine who has a couple young children they take with them when they go to their gym. They said the way they handle this is with "indoor voices" and "outdoor voices". Their gym has a child care gymboree (enclosed large room) and the child must use indoor voices in the play area or they page you-eeek. I looked up some info. on this concept:
http://kristiewells.blogspot.com/2005/12/please-behave-and-use-your-indoor.htmlhttp://childcare.about.com/od/childbehaviorquicktips/qt/voice.htm(It would be nice if my neighbor down the hall practiced this form of parenting.)
I have noticed that early in the morning and late at night there is less noise from the play area because there are fewer children. I think some have early bedtimes. I've also noticed that the gym is more crowded during that time. The library is unusable as such but at least they have a barrier.