Well, SFNE is not worth the trip south IMO. If you want to go, you have to go through at least 3 toll plazas and you might have to endure that pain of the Bostonian rush hour. And SFGadv. While I'venever been there, it must be at least an 5 hour drive to get down there because it takes me about 1 hour to get into Maine, 4 hours to get to NYC, and about an hour through NYC. NYC rush hour traffic is also terrible.
I liked Funtown/Splashtown a lot (Saco, Maine). It has a wonderful CCI woodie (Excalibur), a nice Freefall ride, a good looking Log Flume, an add on waterpark (With a new tower complex for this year), and overall very well kept and parts are themed, if you can forget about the ghetto Galaxi. While the place is small, it should keep you occupied all day.
The park in Old Orchard Beach (Palace Playland) is pretty ghetto, but it has quite a bit of flats and 2 coasters for a credit whores enjoyment.
Also in Miane, there's a small park down In York Beach called York's Wild Kingdom which is actually well kept up by the new owners (Which I know for a fact because I was there last Wednesday) but that's hardly worth going to as it has little rides that most adults can't go on (other than the cool looking Round Up, The Scrambler, the Go Karts, The Ferris Wheel and the Haunted House).
Finally in Maine is a water park called Aquaboggan in Saco, but I have not been to it yet, so I can't tell you what it's like.
Near the Maine Boarder, there's a water park called Water Country In Portsmouth New Hampshire. The place has a large variety of Slides including a Toliet Bowl, vertical Speed Slides, a water play area and a whole lot more!
Also, don't forget about Canobie in Salem, NH, but I believe its about 1 hour from Maine. It includes a classic woodie, an S&S Tower, a Frisbee Ride, a Water Play area, an amazing Shoot The Chutes ride, and a whole lot more!
I hope this helps you on your trip to Maine.