There are a number of girls who are North of Boston who are pretty well reviewed. Also a lot of the traveling girls stay in the Woburn area although be cautious of fakes. Provides some specifics on what you like (top/bottom, ethnicity, are you into size, etc.) and I'll provide any insight I have.

Lavinia has very good reviews.

http://www.eros-boston.com/files/294414.htm

Giselle's reviews are solid

http://www.eros-boston.com/files/274068.htm

Lisa is great as well. Nor sure if Newton is too far south for you.

http://www.eros-boston.com/files/289333.htm

Lavinia is super hung and very functional. She is primarily a top. It wasn't a GFE experience for me but others have received more affection.

Giselle - can't speak to personally, have only read her reviews.

Lisa - is a very good provider. I have enjoyed my sessions with her very much.