The station at Brunswick, ME has two restaurants,
Byrnes' Irish Pub and
Scarlet Begonias. Neither one has much for windows on the track side of the building. A few years ago, La Wife and I took a Father's Day ride on the Maine Eastern along with my oldest stepson and his girlfriend and her parents, plus #1 Granddaughter. (Who is already a railfan.) We had a nice lunch at Byrnes'.
Also on the MERR's Rockland Branch is
Sarah's Cafe on Water St. in Wiscasset, which has a deck overlooking the track. I just noticed they have a glimpse of a train in the painting on their home page.
The MERR offices, including a gift shop, occupy half of the station at Rockland, and the
Trackside Station Restaurant is in the other half of the nicely renovated building. (Which still has jail cells in the basement, from when it was city hall [1959-1994] after MEC gave up passenger service.) They have pretty good nachos.