The big don't -> Armourall. Leaves a greasy residue, and runs down all over your windows if you get caught in the rain, or wash your car! Doesn't last very long either, and does bugger all to actually protect the soft top.
The best product to use, in my opinion and that of many others, is 303 Aerospace protectant. Some Autobahn stores sell it, but double check the bottle before you buy, as they make one for vinyl only, and one for fabric only. I grabbed the first one I saw, and it turned out to be wrong. Can also be bought here -
http://www.waxit.com.au/products.asp?cat=39 and they seem to be one of the few who have the cleaner and protectant together as a 'package'.
I'm sure Waxit would probably also have something suitable for the back window too.