Yeah, after looking at a map, I realized that Quincy and Plimouth Plantation should be on the same day. Also, good idea about stopping in Lexington and Concord on the way to Maine. I had planned to "poke along" on that day, anyway.

missypie- if you are driving to Quincy and Plymouth and back to Boston on that day, I would suggest you consider from Quincy, driving a bit on Route 3A instead of the highway - from Quincy that would take you over the Fore River Bridge,into Hingham, (past the lobster pound; one choice for lunch), or into Hingham harbor/downtown with several good lunch choices - and new england history (loring hall, lincoln statue) - beautiful Worlds End, - and you could drive to Cohasset Common/downtown (art center, historical society, the common wiht a duck pond and old Unitarian Church -both spots where they filmed witches of eastwick, as well as along Cohassets main street, drive the Atlantic Ave/Jerusalem rd to a quaint harbor with Old Salt House restaurant overlooking (lunch choice maybe), and then you can take 3A up rte 228 (which Eleanor Roosevelt called the prettiest street in America) and back to the highway and scoot to Plymouth in about 30 min -
or continue on 3A into Scituate, over the marsh bridge, thru Marshfield and hope on the highway there - or in fact, stay on 3A thru Duxbury and right into Plymouth.

Just an option for seeing some small south shore towns along the way from Quincy to Plymouth instead of flying on the highway if you had time.

Someone also mentioned Salem -
those visiting Boston can also take the ferry from Boston harbor - avoid the drive and get some on water/harbor time too ! www.salemferry.com