Wheel size really isn't much of an issue--- both 700c and 26in work well. 26in wheels are cheaper and thay would fit you better, so go that route.
One thing I find interesting on my touring bikes is 700c wheels on bikes with really small front chainrings. (22-32-44 or 24-34-46 or the like) With gearing like that, a lot of good those tall wheels will do you!
With a Surly frame, you could put on 26 wheels and a higher geared crank for the same gear-inches as a 700c wheeled bike.