Saddles are super personal. I'd see if you can get her in to a professional fitter first, to make sure it is set up 100% correctly. Be ready and willing to have conversation she'd normally save for a night with girlfriends. Seriously. Have her check out thi article:
https://totalwomenscycling.com/...dles-ask-innie-outie The Peleton is more like a spin bike, so you spend time standing, etc. Her position on a road bike will likely be more aggressive, so hips tilted slightly more forward, can't really "sit up" straight.
Some things to look for:
- "just right" padding on the saddle - because padding in the wrong places just squishes into the wrong places
- good padded cycling shorts that fit properly. They need to fit snug all the way into the crotch area, loose fabric slides around and causes chaffing, plus the padding doesn't stay where it is supposed to be
- maybe a cutout - but see the article above regarding that
Tossing all this aside - I've found that a saddle I could count on for "road geometry" riding was a Terry Butterfly. Looking at them now, I'd consider some of their other models too
http://www.terrybicycles.com/...s/Womens-Performance Finally - there is a company in Herndon VA (SportFit Lab) that lets you "rent" saddles to try them out before you buy. They take the cost of the rental away if you purchase - so it's a pretty sweet deal. You can have a few out at once, so you can try / swap and see which one is best.
http://www.sportfit-lab.com/