Despite some grave problems I had with Greyhound recently -- no, because of them -- I was looking around for alternate long-distance bus services. And dang if the UK based Megabus didn't start US service a few days ago. In the Midwest only, I'm afraid, and hubbed out of Chicago. There might be some good options for serious bus-warriors in Minnesota, Wisconsin, Michigan, Indiana, and Ohio, too.
Since Megabus bases its fares on yield management, if you book far in advance, the tickets are very, very cheap. The furthest available tickets (through the end of May) from Chicago to St. Louis, for example, are $1 each one way. And St. Louis is where the UUA General Assembly is this year. That's a five and a half ride, well within my "anything under six hours is fine" rule.
I thought some seminarians in particular might be interested.