I have 2 kids (8yrs and 5yrs). So far, we've found the Mooney to be a great family plane. The kids are small enough that with the four of us, full bags and full fuel, we're just under the gross limit. My wife grumbles a bit about the fact that she can't pack as much as she wants. Our Christmas trip from Atlanta to Houston was the most challenging baggage-wise, but we made that work too. The kids have plenty of room in the backseat for now. They usually play with an iPad or sleep.
The best part is the economy. Anything under 800 miles, we'll beat the airlines "door to door" and for far, far less cost. I usually plan for 155kts on 10.5gph.
The kids will eventually outgrow the backseat of the Mooney, and/or I'll have to start going with less than full fuel. By the time that occurs, the RV-10 I'm building should be ready. If for some reason we outgrow the RV-10, next on my list would be a Bonanza or Baron.
-Aaron