Agree on the Maxxis Re-Fuse.
Run 700x25s on both tandem and single bikes.Tires are quite light (220 grams), 60TPI, 120 PSI, and Kevlar folding bead. Tire has an Aramid layer (generic name for Kevlar) to resist punctures.
In 2011 had ONE flat in 5,600 miles of riding.