The Rivendell Atlantis has 26" wheels on the 47-56cm models. Of course, that's an expensive bike. If you just want durable wheels with fat tires, try setting up an old 70's 27" wheel frame with 700c cyclocross wheels (beefy double-walled rims and mtb hubs). I fit 37mm tires with fenders on my commuter. It's cushy enough that I can ride it down stairs.