If money is no object, the Schwalbe Marathon XR has a long time reputation for puncture resistance and durability. 7000 miles is not unusual. No longer made as they were too good, but still available.
http://www.amazon.com/dp/B00277GJ72/...SIN=B00277GJ72
I've had ok luck with Continental's Touring Plus at half the price, but with less than half the durability of the XR. 3000 miles. Very puncture resistant.
http://www.amazon.com/Continental-To.../dp/B001EIHYVK
The Vittoria Randonneur has been getting some good reviews.
http://www.amazon.com/Vittoria-Rando.../dp/B000OCZVYO
Check out this link for a detailed accounting of tire experience by a guy whose been living on the road for several years. Gotta go down the page a bit to find it.
http://www.crazyguyonabike.com/doc/p...id=81957&v=283