DF and I have been deliberating on the appropriateness of a dawn wedding (6:45am here during the time of year we will be getting married), and we've rented a very nice beach house for the entirety of our guest list (parents, grandparents, siblings, sibling-in-laws, nieces, and nephews only) and will be having the ceremony on the beach outside our front door. There is no way we would even consider such an early affair if we were not hosting sleeping accommodations in close proximity to the ceremony site.
I've also never been a big fan of large gaps between the ceremony and reception. Even if the guests are financially in a position to avail themselves of the local attractions during the downtime, locating such pastimes can prove challenging when one isn't familiar with the area, and wedding finery is often not conducive to such activities in any event.