If you have very little money and some time to get where you are going, Greyhound is a VERY inexpensive way to travel.  Motor Coach travel is an extremely fun way to travel if you desire to travel with groups of other families and save money at the same time.  As far as Cheap Family Fun can tell, Greyhound is currently the only nationwide bus transportation system for getting anywhere you want to go.  However, the other links on this page will take you to companies whom you can contact about charter buses, pre-arranged tours, local and regional bus travel, reserving a personalized motor coach trip for a group, or renting a charter bus.  Each link is the parent company for a variety of groups and services (the description for each is directly from their web site):

American Bus Association -- "The American Bus Association, the trade association of the intercity bus industry, represents the motorcoach industry's interests in Washington, D.C. It also facilitates relationships between North American motorcoach and tour companies and all related segments of the travel and supplier industries and promotes travel by motorcoach to consumers."

Greyhound -- "Greyhound Lines, Inc. is the largest provider of intercity bus transportation, serving more than 2,500 destinations with 17,000 daily departures across the country."

Greyhound Charters -- "Whether you long for the excitement of New York, the nightlife of New Orleans, the fun of Southern California or the tranquillity of the Pacific Northwest, Greyhound Charters is ready to provide you with worry-free ground transportation."

Family Motor Coach Association -- "The Family Motor Coach Association (FMCA) is an international organization for families who own and enjoy the recreational use of motorhomes. A portion of the membership is from the commercial recreational vehicle industry: dealers, manufacturers and RV component suppliers."

National Tour Association --  "The National Tour Association is the premier association for travel professionals who have a keen interest in the packaged travel sector of the industry. The association, which is made up of nearly 4,000 members, brings together those who package travel – group as well as individual trips – with suppliers and destinations who represent the various components of a trip. Although based in North America, our membership spans the globe."

Trailways -- "Trailways®, which has been in existence for almost 70 years, is a regionally based ground transportation system that is comprised of privately owned and operated companies (franchisees). Therefore, unlike the Greyhound system, which specializes in transporting passengers-from coast to coast- Trailways® offers travelers personalized, locally based transportation and travel services."

United Motor Coach Association -- "The United Motorcoach Association ("UMA") is North America's largest association of professional bus and motorcoach companies. Founded in 1971 as the United Bus Owners of America, UMA's membership now includes over 875 motorcoach companies. Another 215 motorcoach manufacturers, suppliers and related businesses are currently "Associate" members of UMA."