I've been reading all the post and had to chime in. Probably the biggest stress of my whole wedding planning was this topic. I made it even more difficult, offering 2 different dates and 2 different hotel(same chain beside each other) as no one told me how these group bookings go.
And my FI's family booked for only 5 days well everyone else is 7 but at least they are coming.
We had so many people coming that put down deposits but when it came to final payment we had around 18-20 people cancel. Now our resort is sold out so no hope of last minute bookings. With 6 weeks out I feel I'm now enjoying it. If I could redo my advice would be to worry about your immediate family , you and him, everyone else is a bonus. And to also choose that date that works for you. We planned around our siblings but we lost others because of being around the holidays.