Worth noting, for tour takers:
Although some bus tours can be, and are, arranged by individual bus owners, the vast majority of bus tours that cross interstate lines are performed by "tour brokers" who are licensed and bonded - and none of them have gone under since the Interstate Commerce Commission rules governing them came into effect in 1935.
By Civil Aeronautics Board rules, all tours in conjunction with charter flights open to the public are supposed to be covered by a bond or escrow account that guarantees protection of the passenger's money until the tour is completed.
The U.S. Tour Operators Association, a national group, was formed in mid-1975 and has now established a "Consumer Protection Fund" of about $175,000. The fund can be drawn on by tour buyers in the event that any of the group's 22 members fails and can't repay money on deposit. The association's Code of Ethics further declares that members are obliged to "expeditiously communicate and explain" to tour buyers any subsitution or deviation from the package as originally advertised. If you think this sounds good, you might want to look for the association name on your tour brochure.