A ride in this plane
https://en.wikipedia.org/wiki/Embraer_E-Jet_family
radically changed my view of what is possible in a small airliner, because it has a squared-off cross section it feels much larger on the inside than a 737... And this is a previous generation plane, now there is
https://en.wikipedia.org/wiki/Embraer_E-Jet_E2_family
and
https://en.wikipedia.org/wiki/Airbus_A220
There's a crisis brewing at America's small airports in that they've really stopped building the sub-50 seat regional jets that serve smaller airports. (In the small city near me, almost every organization lists the local airport as a weakness in a SWOT analysis) Manufacturers know that airliners around 70 seats would be dramatically lower cost to operate than the status quo, enough that prices would drop and service quality would increase and filling the extra seats would be easy. Trouble is the unions won't let the airlines upgrade