D.S.
There's a very nice playground with a fenced in toddler area behind the Gaithersburg City Hall on Summit Ave. There's also a little amphitheater right next to the post office where they have kids' concerts every Mon. and Thurs. morning in the summer, You can make a great morning of it!
http://www.gaithersburgmd.gov/poi/default.asp?POI_ID=1264...