My wife has a modern, Ultegra-equipped road bike, vintage MTB (that doesn't see a lot of off-roading but gets out there occasionally) and a 10 year old comfort bike (kept at her mom's house so she can hop on it for running errands occasionally).

We usually ride together once or twice a week (weekly 10 - 15 mile breakfast ride on Fridays and sometimes another, longer ride on the weekend). She'll ride alone occasionally and will ride with a couple of ladies from our church now and then.

I'm working to get her back to where she was at a little over a year ago when we were doing a 30 - 45 mile ride most weekends. Our younger son heads off to college next fall so I'm hoping that will open up more time for getting her mileage up.