My best answer to this is just do it. You know your kids, so you know what to expect. Blogging about this reminded me of a commercial from a few years back. There's mommy and daddy sitting at the table to dinner and playing footsies. Trying to be all "romantical" with each other. They're lovingly gazing into each others eyes and all of a sudden peas fly their way. They both turn to their toddler who took that moment from them.
We still love our kids nonetheless. And this is what Valentine's Day is all about; sharing the love. There are of course different levels of love. So let the kids spend special time with you and share something special with them on this day. Make it memorable. Dress them up and set your table really nicely if you're celebrating from home. Take pictures. I heard one man on tv saying that he and his son make it about the women in their lives, which is great, but I want my boys to know that yes it feels great to be a giver, but it also feels about as great to receive also. Send the kiddos off to bed (with smiles on their faces and their hearts also) and spend a little QT (quality time) with dad.