In my opinion, the days of having to use a traditional wax are over. For my roof, I usually use ProtectAll Fiberglass Oxidation Remover and Color Restorer (whew!). I find this to be a good product for less frequent use, when you have a little oxidation on the roof. It is both a cleaner and a polish. I also have ProtectAll Polish. This, too is a wipe on, wipe off product.
However, since I bought my Acura about five years ago, I got into the more esoteric products on what are often referred to as the "car nut" websites. You can spend a lot of money on products there, but many are quite good. My two favorites are Klasse All in One, which is good for very light cleaning and sealing; and my absolute favorite, Ultima Paint Guard Plus. The Ultima product is a "wipe-on, walk-away" product. Your vehicle need to be clean and not oxidized, and you wipe on a very little bit of Ultima with an application sponge, and that's it. No wiping off or buffing required. It seems expensive--about $15 for four ounces--but that is enough for 15-20 car applications. In my experience, the Ultima lasts for about six months in a mild climate, although I would expect a shorter time if your class B sits in the Arizona sun all day, every day.