I live about 10 minutes from Canobie Lake Park which is in Salem, NH (I know my little blurb on the left says I live in Boston, but I'm really from the North Boston area) and I love going there at night during the summer. The coasters aren't great, but it's a BEAUTIFUL park and all the rides pretty much suit everyone. Well, I take the coaster comment back - I've been on lots of coasters and the Yankee Cannonball (the woodie there) is still one of my favs - never had a bad ride on it.
As someone said above, a lot depends on where in New England you'll be. I don't really like SFNE because the park isn't always kept up well and besides Superman, there's no reason to go there. BUT, if you're just here visiting then that's the biggest park you'll find around here.
Hey - New England people reading this - Do any of you make the drive to SFGAdv instead? It's about 2 hours from my house to SFNE and I always find it better and more worth it to drive the extra couple hours, pay for a little extra gas and head down to Great Adv. SFNE just does nothing for me - with the exception of Superman, there's no real reason to go there - ESPECIALLY since Six Flags desecrated the Cyclone.