The library by Hamilton Park on 8th st does story hour every Wednesday and Thursday, I forget what time. 10am? Loads of little ones there. Other branches probably do it too.

There are a few children's gyms in the area like the one at Brunswick center, they can do gymnastics classes.

There's also loads of things at American Dream. Most of it is for kids older than 1.5, but it would at least entertain the adults a bit too. Even simple free stuff like some movable sheep statue things for kids to climb on, or the fairy garden area.