Probably the best all-around tire with long tread life is an A/S tire. They usually wear twice as long as max summer tires. This would be my pick of the litter:
http://www.tirerack.com/tires/tires.jsp?tireMake=Continental&tireModel=ExtremeContact+DWS
Good in all conditions while giving up a little max dry grip in favor of long tread life.