Hi Emily,
I'm so sorry to hear you can't get into the restaurants you had hoped to visit, but keep in mind that people change reservations frequently -- don't give up; keep trying. I know personally we had been trying to get into a favorite restaurant and just two weeks ago an opening showed up, so I was delighted and hope you have the same luck (the online reservations makes it easy to check availability).
In case you can't,
Akershus Royal Banquet Hall at Epcot's Norway is quite similar to dining at Cinderella's Royal Table.
1900 Park Fare at the Grand Floridian is another opportunity to dine with Cinderella during dinner.
While it isn't Mickey and friends, Winnie the Pooh and his friends can be found at the
Crystal Palace at the Magic Kingdom. If your heart is set on Mickey,
Mickey's Backyard BBQ at Ft. Wilderness is a hoot (but it does take two dining credits). And at the Beach Club's
Cape May Cafe you can find Minnie, Donald, & Goofy at breakfast.
I hope this helps. Please let us know if you have further questions.