Rt 1 in MA has a Kelly's Roast Beef location in Saugus,MA-see the Roadfood review of the Revere Beach location...or you could head off on Rt 1A and visit that Revere beach Location anyway.
http://www.kellysroastbeef.com/ One of leechef's favorites in the North End of Boston is the Daily Catch restaurant-they have a 2nd location on Rt. 1 in Saugus,MA-fabulous seafood.http://www.dailycatch.com/
Rt 1 in Rowley,MA has the Agawam Diner, a traditional REAL diner still gleaming silver and serving diner specialties since 1940.http://www.dinercity.com/maDiner/northEastMA.html
Also just off Rt.1 on Rt. 1A in Rowley,MA is the American Barbeque.
http://theamericanbarbecue.com/ Rt 1 goes all along the seacoast in northernMA, into NH, and then southern ME.
How far north into Maine will you be travelling?
My family home is in Kennebunkport.
That will help with giving you more suggestions.
DaveM