My curiosity got the best of me so I went out and measured:

28 mm Continental Ultra Gatorskins measured 27.5 mm @ 95psi
32 mm Schwalbe Marathons measured 31 mm @ 85-90 psi
Both pairs of tires are mounted on Velocity Dyad rims, and measured with calipers at widest point.

My wife got a pair of 32 mm Continental Ultra Gatorskins for Christmas (that is what she wanted), but I have not mounted them on her bike yet.