Well I was speaking generally about things one does with kids, but actually the library is right there; the Freedom Trail kicks off at the Common, which is a short stroll; the Science Museum is on the green line; and even the aquarium is easy when you green line to GC and walk a bit. With the shops and Comm Ave and close to Fenway and Beacon Hill and the green line running right through, I think it’s the best place to stay. YMMV.