I have a fairly short commute back and forth to work of less then 10 miles.. all down hill in the mornings, all up hill in the evenings. Mostly asphalt on the roads while the town streets are cement with lots of patched cracks and joints for off the seat jolts. The asphalt shoulder riding area has a lot of stones, glass, etc. that so far have not given me flats, but I try to keep a sharp eye out for obstacles.
My last commuter bike was a KHS Urban-X with 26"x1.5 60# Kenda Kwest tires with quite a bit of tread, while my current bike is a Specialized Sirrus Sport with 700x32c tires that are fairly smooth and I keep them at about 80-90# I've noticed a big difference in rolling resistance with the new bike, much faster and seems much easier to get up the hills.. but it is also harsher, I can feel a lot more vibration and the bumps come through more and the handling doesn't feel quite as easy as with the KHS although it feels faster, is this because of the narrower tires and lack of heavier tread?