What about Shady Glen ? How big did that chain get ?
Not sure why you're comparing Shady Glen to the massive chain of Howard Johnson restaurants. Although when I was a child in the 1960s, I remember HoJo's food was similarly delicious.
Thankfully, Shady Glen's two wonderful restaurants live on in Manchester, CT. From what I've seen, they get REALLY crowded at times, so I have to assume the 2-restaurant "chain" is doing well.
I have many relatives who have moved out of CT (years ago). But when they visit family and friends in CT, they *always* make sure to stop at Shady Glen. I would do the same.