Trek420 is 5 foot and a whisper, she was happily toodling around on a 42 cm Surly Long Haul Trucker. It had 26 inch wheels, she really liked it. She wants to get one for the next ALC. http://www.surlybikes.com/lht_comp.html

The Surly Cross Check goes down to a 42 cm, too. http://www.surlybikes.com/crosscheck_comp.html

Both do wider-than-road tires and are super comfy steel. (and have very lovely lugged forks)