It's an interesting concept. A day that used to involve buying dad a new tie, or so the cliche went. But most dad's don't wear ties anymore, so now we take dad to Outback or some other manly place for brunch or dinner as way of saying "thanks for being a dad, dad."
But for me, Father's Day is a reminder to put things in perspective. No matter how well or how crappy work is going, no matter how fancy a vacation you have planned for the summer or how concerned you are about paying the bills, no matter how much or how little you and your wife can enjoy a quiet moment here and there, if you are a father, there's nothing more important than the relationship you have with your kids.
My dad traveled often for work, and when he was around, the stress of his job and who knows what else kept him from seeming happy much of the time. I'm afraid I'm like him in that way. I'm writing this in the hopes that by admitting to that publicly, I'll somehow force myself to be better with my kids - to be more present, more involved, and more outwardly happy with them. They are great kids, they want me to do stuff with them, and I want to be there for them, physically, and otherwise.
I hope your Father's Day is a good one. This father is going to do a better job on the everyday.