Originally Posted by spare_wheel

Gah!

The OP did not ask what size tire they should purchase. They specifically asked for recommendations for 700x23. To illustrate how easy it is to do this:

Money is no object: Conti 4 Seasons.
Cheap kevlar clincher with reasonable protection: Rubino Pro II/III (as low as $25 on sale)
Cheap impregnable wire bead clincher: Serfas Survivor (far better protection than gatorskins and only a touch heavier)

When riding on tarmac preferred tire size is influenced by preference and riding style rather than some dogmatic platonic ideal.