Regarding 40' buses in the city, there are plenty of 40' school and transit buses on the road in cities every day.
While there were some minor challenges, I successfully navigated Seattle, Los Angeles, Boston and New York in my 40' bus.
I am leaving Denver off of the "successful" list after having to back up a full city block at 5:15pm on a Friday...... I was 13' tall and encountered a low overpass..... People were SO supportive. They honked and told me "you're number one" using universal sign language...
If the bus was 25' long I would have had the same trouble. It was the height that created the issue.
IMHO: A 40" bus is generally not much more difficult to drive than a 25'-30' bus. Parking is a different story. I could fit the shortie in a normal parking space. My 40 ' bus fit nicely in about 6-8 parking spaces