I wash mine when it is really dirty with Turtle Wax Zip Wax car wash.  I use a Swobbit on an extended pole as most brushes, even those advertised as 'soft' will put small swirl marks in the clear coat.  Roof gets washed at least 3 times per year and coated with 303 twice.  I use a squeege on a pole to get most of the water off after washing and a synthetic chamois to wipe the lower sections and any chrome and the windows.  
Aluminum wheels get polished with Wicked Metal Polish at least twice a year.  
Between washings (if it is not really cruddy/muddy and primarily dusty, I use a waterless product called No Wet which is a dry wash and wax that is best used with microfiber rags/towels.  It does not scratch and leaves a really nice shine.
Now as I get older, I am hating to drag the ladder around the coach so I just ordered the kit from Aero Cosmetics that is recommended by many on this forum.  It uses a reversible microfiber mop and Aero's own blend of waterless wash/wax formula.  It was developed for the aircraft industry.  I am anxious to try it.