I have family visiting from out of town & it's supposed to be rainy today. I can think of all the Boston things to do (Aquarium, Children's Museum, etc) but we had originally planned to do something "historical" & outdoors (like Walden Pond or the battle field near Concord) or just something "typically New England" like maple sugaring, which I realize is over. Anything along those lines that's relatively closet to Boston (we have two kids who still don't like to nap out).
Mama to my little busy bee.
I'm a big fan of Salem, so that's my vote. They have a really awesome art museum (Peabody if I remember correctly) that had a lot of kid friendly stuff when I was there. There are also tons of Salem witch trial related museums. If it's not too cold or icky out, we also liked to just walk around town.
I've never been to Drumlin Farms myself, but I have several friends who have worked there and I've heard great things about it.