The problem overall that I see here is that family time is extremely important, more important than we as a society value it at. Reading the Original post, it sounds like he would not miss any school because of this, so I think the better thing to do is to find out WHY he doesn't want to go. My best guess is it involves a significant other, but that is just a guess. If that is the case, I would suggest still having him go, pointing out that there will be time for them to be together AFTER family time. If there are other reasons, then address them as well. If he is going to miss school, speak with his teachers and get work for him to do so that he won't fall behind, most teachers are willing to do this if you give them enough notice so they aren't rushing at the last second to put something together.
In the end though it comes down to it you could force him to go and be miserable, but not have him come and you feeling like you are missing him being there, but overall a more enjoyable time for everyone.