I agree that everyone would handle their own travel arrangements personally and then the organizer (like I said, I'd help with NY or Orlando) would (i) post info regarding hotels, (ii) come up with an itinerary (sp?) of sites and other local activities of interest for the weekend (so that people traveling to the destination can make a mini-vacation of the opening weekend), (iii) post info and help organize catching the movie (I don't know how cooperative theatres are with booking groups for big event films on the opening weekend, so this will have to be explored), and (iv) possibly help put together at least one get-together (like a dinner) for the group.
As to the film, one problem would be picking a time. The film will most likely open mid-week -- before some people can complete their traveling. So some consensus would have to be reached as to when would be best time to see the movie -- at the beginning or end of the weekend.
As to the locale, planning will be dictated by the destination.
For example, if Orlando is picked, I would propose a number or WDW and non-Disney resorts for people to stay. One neat possiblity would be to get a number of campsites at Fort Wilderness Campground and have a group BBQ at some point during the weekend (incidentally, one of the better resorts, the Wildneress Lodge is in walking distance of the campground for those disinclined to camp). One day -- probably a Satuday -- would be spent in the Parks, most likely MGM. We could set a time to see the stunt show as a group.
If New York is picked, I could post a number of good places to stay and good attactions in and around the city. I could organize a great hike up at Harriman State park just up the Hudson from the City. And again, we'd have to settle on a time and catch the film some time during the weekend.