Just wanted to point out that one of your planned stops--the Longfellow House--will not be open during your visit. It does not open for the season until late May. Their website will tell you that the grounds and garden are open year-round, but they are very small and not worth your time on their own.

The Boston Calendar does weekly lists. You can sometimes find good ideas in Boston Magazine, too.

This town has sorely needed an arts and entertainment-focused publication since the Boston Phoenix folded (a decade ago now). That was the go-to place for listings (and also thoughtful reviews) for many years. May it RIP along with the Improper Bostonian and the Weekly Dig.