I run 700x25 Armadillos over railroad tracks (recessed, though), potholes, broken glass, etc etc. No problems. I find that the 25s are skinny enough to be fast, but thick enought to take care of most of what the road can throw at me. The Armadillos are a tad heavy...but what do I care? I'm already running a rack with loaded down panniers, and SKS commuter fenders.

I think 23mm Conti Ultra Sports may be a bit "light duty" for a commute. I'm certain they're great in a decently groomed race route though!