I run Schwalbe Marathon Plus Tour 26x1.75 tires on my trekking/touring bike. It's a rigid 26" MTB with racks and stuff for touring that sees asphalt about 75% of the time. These tires give you a good balance of smooth rolling on asphalt and some off-road capability. There is my lone review of these tires on Universal Cycles. But if you don't care for off-road then there are even better 26 road tires like the Schwalbe Durano 26x1.10. There are even slicks for 26 wheels. I would have gone with something thinner and slicker (?) but my treks sometimes take me on moderate forest trails or country dirt roads so I want some off road capability.

Let me tell you from experience: I had a 700 touring bike with 700x32 tires, didn't care much for road geometry so I sold it and the current 26" MTB touring bike with the above tires works just as well on long road trips, with the added benefit of slightly lower gearing for long climbs with 60lbs of gear due to smaller wheel size. On both bikes my daily average speed while touring is the same. So bigger wheels didn't make any difference for me.