I ride Continental Top Touring 2000 700x37 tires on my commuter. I actually think they roll pretty fast when I run them at their maximum pressure (75psi). I also run them at 50psi or so when I want more comfort on really chunky stuff.

Sure you can ride the occasional trail or dirt road on skinnier tires, but the best thing about the wider tires like the 700x37 or 38 is the wide range of pressures you can run. The Panaracer Pasela 700x37 takes up to 90psi, but you can also run it at 40psi or so without fear of a pinch flat. Then again if you ride on roads 95% of the time, you don't need such a wide tire.

Sean