Everyone in my area uses Easton Pools. They are in Easton, a suburb of Boston. Not sure how far north they work.
If you are getting a pool, get a heater. After August, the water gets very cold overnight! Some of my friends have salt-water pools and have had a good experience. (No chlorine).
I live near Boston! Just a suggestion - buy a roof rake for snow now when they are cheap. You never know when you need one and when there is a bad winter, they are hard to find.
Good luck!