I have two young kids too. Also, in South Florida we are prone to some really nasty weather activity this time of the year and, of course, it seems as if things hit at the times I have planned a ride. When this happens, I resort to the trainer which I use outside under the cover of my roof as I have a very large overhang area. Since I never ride on the road with headphones on, the trainer gives me the opportunity to listen to tunes which is an interesting change.
I agree though, it takes discipline to do it. I have found however, that I retain much of my strength for the road rides when I keep up on the trainer. I ride with higher cadence on the road, 90rpm or above, than I do on the trainer where after spinning at my road cadence for a warm up I go to higher resistance and lower cadence. I have one extra, but important, motivating factor. I have a family history of high blood pressure and, at 54, find mine finally creeping up in spite of my riding. I still am able to stay off the medicine and riding is the way I have been doing it. My blood pressure always drops significantly after riding so I make sure to get on the trainer for one hour on those days I can't get out on the road.