You do not say what kind of paint job the coach has, BUT! if you have a full body paint job with several coats of clear coat, you have to be very carful what kind of wax you use because of the clear coat. Some waxes will actually dull the look on the clear coat.
My coach is eleven years old now and all I do is wash it with a dry wash and when it is ready for a wax job which is like once every year. I go to WalMart and buy liquid Blue Coral, mix it with water and pressure wash it. Then I just get a squeegee and wipe it as much as possible, followed by a dry cloth on spots I could not get with the squeegee. It looks like the day I bought the coach. Paint job has held really good for eleven years.