For the most part it's not so much that the abs are sexy.. it's their overall body that is sexy. These girls weight lift and that's how they get their abs.. but they also get an amazing lower body and overall figure *drools*
Girls who work out naturally (no steroids) A LOT and achieve extreme body fitness usually retain their feminism despite their increased muscularity--- like the 4 girls I showed above.
Just google fitness models, and you'll see there are plenty of sexy women with nice abs.
Obviously guys opinions are gonna vary. But I think if you have that level of fitness, and therefore great legs, and a healthy/sexy composition, that once they see your overall body they'll be so full of lust that you could have a six pack and they wouldn't care.