re: Best time of year to visit Boston?

I've been in early October, it's great. The Sox might still be playing??
The Pats, Bruins & Celtics are definitely playing, the kids are mostly in school, Nantucket and Cape Cod are slow but not closed down, the foliage is changing (or changed ).

No snow or ice or crowds. I stay at the Marriott Long Wharf downtown, there's a subway station right there but you can walk to a bunch of things from that location.

Have a great trip.