I am home with my kid too. She likes riding in her "go-kart." I have a friction drive kit on the main bike I use, so I can motor up the hills and can get back quickly if I'm worn out.
Look for other home dads in your area, it might be more fun if the kids have playmates, and the guys can talk about bikes or not feel left behind by all their bike friends. The wives will think its cool if they get a girls-day-out out of it too.
My wife doesn't exercise. She likes books and movies. She won't go to the park with us, and I can't even get her outside with a motor on her bike. It's always "too hot" or "too cold." So that's my goal for 2012, just to spend a day at the park with kid and wife and not hear 1 compliant after 2 miles that she wants to go home.
My goal is to remember what it feels like not to wake up feeling drained, tired, or foggy. I have no mileage goal other than to get out of the house and do a couple charity rides and some bar-hopping, and make at least 1 trip to Cedar Hill State Park this year.