A cruise on the Mount Washington is ALWAYS a great day, regardless of weather. Great opportunity to walk around, mi/mingle, etc.
How can you avoid Funspot? Something for all ages, not just kids. Go early while the kids are in school, though.
Next door is Winnipesaukee Museum. Check first for hours.
Farther away is the Libby Museum and the NH Boat Museum and the Wright Museum, if you're driving around the lake. And Castle in the Clouds. Obviously check for fall hours.
Are there any "party Craft" stores around, where you all get to make or paint something to take home?
It's warm, so light occasional drizzle shouldn't stop many outdoor activities, and later, you can brag that "We did it in the rain".
State Parks are free or cheap and you can usually find a covered pavilion for an outdoor picnic.
Echo Lake in Conway. If it's too wet, you can do all that tax free shopping. "Echo Lake State Park is a great place to take the family for a swim and picnic. A scenic trail around the lake provides great views of sheer, 700-foot Cathedral Ledge which towers over the lake. A mile-long auto road and hiking trails lead to the top of Cathedral Ledge where views across the Saco River Valley to the White Mountains can be enjoyed. Both Cathedral and nearby White Horse ledges are popular rock and ice climbing walls."
Your best fun is probably each other, and the activity will be secondary. Try the "events" page on
www.visitNH.com.