You might consider looking at access to good but affordable child care. For the dogs - a safe place to walk and exercise would be ideal - however Montgomery county dog parks are in Wheaton and Germantown [1]. IMHO Bethesda/Rockville are going to be safer than Silver Spring/Wheaton but you'll be able to afford more space in Silver Spring/Wheaton. With regard to public transit, funding cutbacks means that some bus routes might be cut back or eliminate. Bethesda, Silver Spring, Wheaton, and Rockville have been redesigned to be mixed use transit-hub commercial centers.
Another place you might consider is Takoma Park, MD (which has a metro station, parks, and
a quirky mom-n-pop-store no-nuke community).
[1]
Montgomery Parks: Dog Parks - Dog Parks in Montgomery County