Intersection of rt 7 and 23 on south side of town (the turn to go to catamount actually) there is a pizza house called Manhatten Pizza---eat in or take with---it is very good pizza.
On the strip with friendly's, McDonalds, Kmart and the Pete's Ford there are a few sandwich shops and a place called 3 brothers that are decent.
If you like cheesecake---you have to go downtown---there is a place across the parking lot from the big stone church---same side of main street---called Cheesecake Charlies. Expensive, but great cheesecake. They also are a decent deli---good but slightly pricey.
down the street same side is a Subway shop.
Further down main street, same side---right next to Searles Castle there is another sandwich shop---I forget the name---a must see because of atmosphere. I heard it may have closed, but worth a look. It is called simply "the deli"!
Railroad street has places of the day---new stuff all the time---you might find something by just walking around.
I used to spend a lot of work/week days there---never ate dinner in Gt Barrington. I can't help much for dinner places except for maybe 3 bro's and manhatten Pizza.