I use Specialized Armadillos 700x23 on my road bike, and I love them. Over 3 years and 15k miles on one set, got a new set and put about 3k on them so far - no flats except one where the inner tube broke at the seam (after having the same inner tube in for almost 4 years I'm not really surprised!)

This is commuting in central london, over all sorts of rubbish (I often pick glass / stones out of my tyres).

Daven