Hi Amber,
Disney hasn't officially released many details about the plans for special events on Oct 1st. I've seen what non-official sites are reporting. @DisneyParks tweeted on 9-26-11 "Magic Kingdom will celebrate its 40th anniversary Oct. 1 with special merchandise, a character cavalcade, a sing along and more." It would seem that there may be some special surprises that day. If only we knew for sure but that would take the fun out of the surprises, right?
I don't envy your decision. If your daughters know about your reservations at Cinderella's Royal Table & are super excited, they may not like the idea of missing breakfast with the princesses. To them that might be way more exciting than any special presentations.
As an adult & a complete Disney freak, I want to soak up any special events - no matter how large or small they might be that day.
If your family members are huge Disney fans & don't want to miss out on the possibility of special surprises, then being out & about in the park is where I'd want to be. I'll be there & no matter what surprises they may or may not have planned, it won't matter. I'll be there on a day that made history 40 years ago.
If you plan to visit WDW again in the future, you could always skip CRT this time & try to get reservations for your next visit. However, visiting CRT while your daughters are still in their young princess loving years, may be all the magic you need that day.
If you do decide to keep your CRT reservations, allow plenty of time to get through security & any possible crowds outside the gates that day. If you're on twitter, I'd follow @DisneyParks and @WaltDisneyWorld - official Disney twitter accounts. Also keep an eye on the
Disney Parks Blog for updates.
Wishing you minnie magical memories :-) Allison