My wife is 5'5" but with short legs. I checked stand-over height for lots of bikes and found that the Spec Safire was one of the lowest available, along with the Orange bikes.
Trance & Cyphur was one of the worst, she hardly had any stand-over clearance, even on the small frames.
[Geek]
Here's my ladies bike list of standover height (inches) in ascending order, made it about 12months ago:
Titus Motolite XS 26.3
Orange Five 14" Small 26.8
Orange Five Diva 14" Short 26.8
Specialized 2009 Safire S 27.2
Titus Motolite S 27.3
Rocky Mountain Altitutude 27.3
Transition Covert Medium 27.5
Titus FTM 27.6
Specialized 2009 Safire M 27.6
Transition Covert Small 27.6
Specialized Stumpjumper S 27.8
Orange Five 16" Medium 28.2
Santa Cruz Juliana 28.7
Santa Cruz Heckler Small 07 29.0
Intense 5.5 Small 29.0
Yeti 575 (08) Small 29.0
Orange Five Diva 14" Long 29.1
Titus Motolite M 29.3
Santa Cruz Heckler Medium 07 29.5
Norco Fluid LT M 29.7
Giant Trance X S 16" 30.9
Rocky Mountain Slayer SXC 16" Med 31.1
Giant Trance X M 31.4
Giant Cyphur M 18" 31.8
[/Geek]
She ended up with a Safire and loves it, very capable.