In MA you will be limited if you have anything larger than 17 ft with a decent sized motor. Not that many lakes in Eastern MA than can take large boats. That said here are a few places.
Lake Quinsigamond - Worcestor. Public boat ramp. $8
Lake Cochituate - Natick. State park has a ramp. $5
Charles River out into Boston Harbor - Allston. No fee at community boating. Parking can get full early on weekends. Can also go in at Terminal Street.
Merrimack River - Put in at Salisbury and head inland. State park has ramp. $12
The only place I have boated in Conn is in the Conn River. You can in at East Haddam and head towards the ocean.
If you go up to NH I would recommend Winnisquam. State boat ramp in Laconia. Get there before 10:00 on weekends and you will usually be OK. If there is no parking you can head to Winnisquam Marine and most of the time they are cool and will let you use their ramp however parking is limited. You used to be able to park down the street in this little field but they have cut way back on how much space can be used.