It really depends. I'd get there at least an hour beforehand, but I don't think 2 hours is really needed. The last two times I've flown out of Logan (last year), I did that self check in thing with the computers and got through security very quickly. They did make me take off my shoes but that only took about 5 minutes.
I think it depends on the size of your group too. It was just myself and another adult the last two times I went.