Solid All mountain skis.....
Line Celebrity 90 (or 100 if they can handle a wider ski)
K2 Payback ( not a twin, but this ski can do EVERYTHING else, their factory series really isn't stiff enough for me to call it an all mountain, all of them don't do so hot at high speeds)
Salomon Geisha (could be a bit wide if she is newer)
Salomon Lord (yeah, it's a men's ski, but it does really really well as an all mountain in the shorter lengths)
Head Wildone (they took the metal out of it to make it a bit less aggressive, not a twin, but it kills it as an all mountain)
Elan Bliss (technically more of a powder ski, but this year's has no rocker and normal camber and the thing shreds)
Stokli Rotor (you can't afford this)
This based off the decision to me that an all mountain should be able to do 2 things, survive/hold its own on a powder day, but Shred the mountain to pieces on any other day. You can ski backwards on any ski I used to do it on my race skis all the time. So the twin is really only needed if you think she is going to be taking her all mountain into the park and landing backwards any time soon.
In which case, I'd say the Celebrity 90, Paypack, and Lord are good places to start, all around 90 underfoot with a pretty decent sidecut that makes turning manageable for someone knewer but they all kill it on a powder day and wont leave her behind.