of course, the Green line is the line by Fenway (Kenmore on the B, C, and D branches, Fenway on the D (Riverside), St Mary's on the C (Cleveland Circle), and ??? on the B (Boston College)). Don't listen to half smokes on this one. The Green line is LRVs that go through a subway then on the surface. I grew up on the green line, take it still. The whole system is a bit grimey. Feel free to take your Dunkin Donuts coffee on board the T.
South Shore - - - - - > Drive to Braintree - - - - - > Take Red Line - - - - - > Transfer to Green Line - - - - - > Enjoy Nationals beating Red Sox
Perfect vacation!