I wear shorts except when it gets below about 30 or 40 F to minimize sweating. Or if there are bugs. If I'm hiking in a lot of sun I might wear pants.
I make my own - Supplex - similar to Roger's article and I have an article in the works.
I don't know if anyone sells Supplex pants, although I have worn some from Ex Officio that are similar enough - nylon, tight weave, kind of a cottony feel.
I would never wear convertibles. I prefer more simple - lighter - drapes better. And I always take one pair of shorts and one pair of pants anyway. If something happened to one I have the other as a backup.
I've worn a swimsuit before. That worked okay, but I prefer the Supplex fabric.