My daughter just attended a wedding on the weekend of the 4th this year. I wondered about it, but his family is from the Seattle area and hers are from Baltimore, where the wedding took place. I figured a long weekend was maybe easier for more people to attend a distant wedding.
Neither of us is from the DC area so we had lots of family from out of state. I made reservations at the local budget hotel and most of them came and turned it into a mini vacation. Of course it helps to live in a major tourist destination.