I've had opportunities offered by companies to stay an extra few days in places at their expense, on a few rare occasions I've taken them up on it, I've even brought my wife along. But honestly, most of the time I just don't have the motivation and interest to be alone in a city and knackered from working, I just want to get home to be with my family.
Don't get me wrong, I love travelling for leisure with my family, but on my terms and to my own schedule.