Well, there is NO bad weekend. . .
Check their schedule for special events, there's usually quite a bit going in through the year. If you see something you like, go for it.
If you don't mind crowds, pick a weekend in the summertime. Lots of families, i.e. kiddies, and there's lots for 'em to do both in the Museum and the Village.
If you want a bit quieter less crowded time, consider mid September or later, after school starts. We've done both, when the kids were home, and then just the wife and me. Never had a bad experience at Henry's Place.