Stephanie,
First off, if you have reservations there you should be getting a notification from Disney to that effect, along with an alternate location that they have secured for you. You don't have to take that reservation if the restaurant is not interesting to you, but nevertheless you should get that offer.
As for great replacements, I have three. They are not in the Magic Kingdom, but are all in the monorail resorts that are just a quick ride from the front of the park.
1900 Park Fare (Grand Floridian)- Breakfast with Mary Poppins, Alice in Wonderland, and many other characters. I just returned there a few weeks ago, and the food was better than I ever remembered. And the character interaction was one of the best of our whole visit.
'Ohana (Polynesian) - The food is fine, though nothings special. But the fun and exotic setting, as well as the characters (Mickey and friends, Lilo & Stitch) are good.
Chef Mickey's (Contemporary) - Mickey shuttles between these two meals to say hi to all the kids, and while the food is good, it is more about the setting and characters.
Any of these would be great!
Have a magical (and delicious) vacation!