I wouldn't recommend using glass cleaner on your plastic windows. It fogs them up pretty bad. I usually use Simple Green to clean the top, but I've noticed I've gotten a couple spots that look like bleach spots, so I'm wondering if I need to start diluting a little.
I use the same wax that I use on my Jeep o clean my windows. I use a damp towel to wipe them down, then I wax them with Mothers. Every few months I'll bring the windows inside the house, and I'll sit down in the floor and wax windows.