I like my Schwalbe Marathons. I have them on the Tandem (26 X 35), my mountain bike which is set up for pavement riding usually (26 X 35), and my 520 (700 x x35). I cannot remember the last flat that I had! This past Christmas, I took the 520 to Florida with me, but was having a hard time getting the tires into the box, so I left them at home and picked up a pair of Bontager AW1's. They were fine but I don't have long term experience with them. The ride was nice, and they supposingly have some puncture resistance. The Marathons OTOH, are quite heavy- 1.5 pounds each!

On a touring bike, are you really trying to get super low rolling resistance, quick, agile, nimble, high performance? I prefer reliable, good ride, flat resistant personally.