Coniti Four Seasons. Excellent flat protection, and much better wet weather grip and handling than the GatorSkin. They are light too.

I've found that there is a huge difference in speed going from 32mm to 28mm, but no major difference in grip. YMMV.

Also, Schwalbe has come out with the Marathon Supreme in 28mm. I haven't tried them so I can't comment, but my wife loves her 32mm on her commuter.