I've got two bikes, a Bullitt cargo bike and a Brompton. I'm a regular transportation cyclist, and my wife isn't. She doesn't want to spend any money on a bike of her own, but she likes the Brompton quite a bit.
So far, she hasn't ridden more than a couple of miles on the thing, but she's making noises that maybe some more regular, longer (10 miles) family rides might be possible. I'd be on the cargo bike, she'd ride the Brompton.
Only issue is I've got a Brooks Flyer on the bike, and I wonder if the saddle will get 'confused' being ridden by two people on a regular basis.