I've got well over 3,000 miles on a set of Schwalbe Marathon Plus 25mms over the last year. In that same time I've had one inexplicable flat in about 1000 miles on a regular set of Schwalbe Marathonns (26x1.75 tire) and multiple flats over 500ish miles on a set of Conti Gatorskin 23mms. If I'm riding any distance, I feel most secure riding on the Marathon Plus tires.
Keith