Well the only time I ever seen a big heap of Coaches was one time in Las Venturas, along The Strip. There were literally handfuls of Coaches. (That is handfuls: if each Coach represented one finger/thumb).
FLoFTFROG Inc. Trivia: In February 2008, a Lithia, Florida woman claims an 'Elmo Knows Your Name' doll threatened to kill her son by name.
For a long time I thought that I'd never seen a bus in this game, too. Then I found out that the Bus in GTA:SA looks VERY similar to the Coach. In the previous GTAs the Bus looked more like a school bus. I've actually seen a lot of Buses.
"Kids: if you REALLY want to piss off your parents, buy real estate in an imaginary place!" -Busdriver
Yes, buses can be a ***** to find. Driving around the docks in a Coach seems to work well enough, but it can sometimes take half an hour. But it's worth it, because it makes for some sweet Homie road trips to famous San Andreas landmarks.