I did work for Greyhound from 1971 to 1973, but not as a driver. I did however get a few chances to operate Scenicruiser's for a brief period when I was in maintenance....
I think that the larger the bus, the better....more seats equal lower expense. It costs virtually the same to operate a forty-five footer as a thirty-five footer, at least in driver and fuel expense.....
As you probably know, my current employer operates many traditional rural local routes, in addition to our express routes. The local routes amazingly still carry pretty well, even though most of the population along it have cars, many living in The City, do not, and use our service to visit there. Also the residents of the rural area's, avoid driving to The City, due to the high traffic, high expense of parking, etc., when they come down to visit or to see shows, etc. And there is little competition, as most start-ups are only interested in going after high volume express routes....