i have kenda 838s on my Specialized. i like them a lot.. get a "fat tire" look and added comfort if you run the pressure low. plus they roll way better than knobbies. i use them around town and so far so good.. not sure how durable they are since i haven't put tons of miles on them, but no flats so far

http://www.amazon.com/Kenda-Bicycle-.../dp/B002DX1DWG