I like my Conti 28mm Ultra Gatorskins quite well for loaded touring.

BTW: I don't see the Conti Grand Prix 4 season as an entirely stupid idea. Wear might be a bigger or smaller issue depending on where and how long you tour, but replacing the rear tire twice and the front once on a ~5000 mile tour is probably what we are talking about. That isn't really a huge problem if touring in the US or Europe, and the ride would probably be sweet. Still I am inclined to pick something a bit more durable, like the Gatorskins I mentioned above.