If you can borrow a tandem from your dad and see how the logistics work in your building and see how you and your wife take to it, that might be the way to start out. That said, is your dad's tandem set up for beginning riders? Does it have 2" wide tires? Does it have straight or downturn handlebars? If there is a bike shop nearby, it might be worth it to pay the bike shop to adjust a borrowed bike to you and your wife. Being comfortable on the bike will have a lot to do with whether you enjoy it.

Based on your description of you and your wife, trying a tandem seems like a reasonable idea.