Back when my parent's first got divorced, my father would come up on Fridays on his weekends and sleep on my mom's couch so that he could spend as much of Saturday with us as possible (now, he's got a wife and it would be inappropriate for him to sleep on her couch). By the time he got there on Fridays, it was, at best, bedtime for my siblings.
Which meant that I got to spend time with him alone on Friday nights. Mostly, we would watch TV together. We'd talk some. But it was my special time with my dad. And it meant (and still means) a lot to me.
The year I graduated high school, we started spending a large portion of our summer with him. It was nice, because again after my siblings went to bed, I got to spend some time with my dad. And again, it was a wonderful and special time, and has always had a special place in my heart.
So, Happy Father's Day Daddy.