I have a wife, 3 year old twin girls, and two dogs.
My family even jacks my commute time!
I can only ride M, Tu, F due to the wife's yoga teaching schedule. I'm _almost_ fast enough to make it home on the bike as fast as I would in the car, but even at best there's no wiggle room for a flat or anything. So for now, I'm stuck with those three weekdays.
On weekends, I try to turn every errand into a bike ride. We do have a trailer and my wife has a good bike (better after I did some mech work this weekend), but it's hard to do too much in this heat with little ones. They do love the trailer though.
A few weeks ago I bought some stuff at Office Depot, then rode to the grocery store and bought $200 of groceries and fit it all in the Back Rollers. There was a full-size baguette sticking up out of the corner like a flag. I wish I had taken a picture. I bet the bike + me + the groceries weighed almost 300 lbs.
My family is very supportive of my riding, but it still has to fit within our very tough life schedules. I keep telling myself it'll get easier as the girls get older. I'm already dreaming of a trip touring the French countryside on two tandem bikes when the girls are 9 or 10.