For a basic trainer, I'd look at a magnetic resistance unit. The CycleOps Mag gets great reviews, I have the fluid one which is considerably more expensive, but love it.
One option is just trolling her local CL and buy the best rated mag trainer that comes up. That way she can just get a sense of indoor training (not for everyone!) and the relative loudness of the mag (effective, relatively expensive, but loud) before she commits to something new/expensive.
Sit bones = ~135 mm, saddles that work ~ 155cm/6.1 in wide
2003 da Vinci (custom road/all-rounder)/Terry Butterfly Ti
1994 Gary Fisher Nirvana (vintage MTB/commuter)/Terry Butterfly Chromoly
1991 Terry Symmetry (NOS frame/fork, project in progress)
1973 Raleigh Super Course (project in progress)