+1 for the Marathon Racers.
According to Schwalbe, the Racers are the fastest rolling tire in the Marathon line. I have one on my LHT with over 6,000 miles on it, about half of that loaded, and it still has plenty of wear left. I'll probably take it on this summer's tour, at which point it will have over 7,000 miles on it. It started on the front, then got swapped to the rear at about 4,700 miles. It still looked almost new at that point. The original rear Racer had about 4,700 miles on it when I replaced it with a new Racer. I did that only because I was about to start a tour and it looked a little worn, although it still had life left. I still carry it as a spare. In all that time, I've had had two flats -- one on each tire -- 1 from a Michelin wire, and one from glass in wet weather.