Yikes! Thanks for the update--I hadn't checked the WDW calendar in a while, and they did indeed change 9/30 from a PM EMH night to a 7 pm close. Now I can't decide whether to do the 9/30 party or the 10/4 party or both. My dh much preferes the parks after dark, and there aren't a lot of late evenings during our weeks, so maybe this would be a good compromise. But we've never been to any of the special events before, so can I pick your expert brains?
1. Is it worth it (3A/1C=~$150) to do it twice? Blackbunny, I see you're going 3 times.

Do you do different things each time? Wear different costumes? Will we have to skip things if we only go once?
2. I have ADR's at resorts in the MK area for both nights around 5:00, and am feeling anxious about not getting into the park until nearly 7:00. Will I really feel like I'm a "late arrival" if I don't? Or are most people who enter early using the extra time for dinner at LTT or CP?
3. If we only do one, I'm assuming the 10/4 (Thu) party will be less busy than the 9/30 (Sun) one. But Sunday isn't Friday or Saturday, and it's pretty early in the schedule, so does anyone think the difference would be noticable, or that one would be preferable to the other?
4. Since our MNSSHP night will be a "no parks" day for us, we'll likely hit BB, TL or DQ during the day. I've got to assume that 10/4 will be slower at the minor parks, since 9/30 is a weekend. Would that factor into your decision at all?
TIA for your help. I'm so glad I found this thread--I always learn more from the DIS than from any official source!