Hello Jessica! A character dinner sounds like a great way to begin your vacation! If you would like to dine at one of the resorts, you have two options - both would be very convenient for you.
Your first option would be dinner at 1900 Park Fare at the Grand Floridian.
Cinderella's Happily Ever After Dinner is a buffet meal with a wide selection of food. Typical characters at this meal include Cinderella, Prince Charming, and Cinderella's wicked family members - Lady Tremaine, Anastasia and Drizella. A large organ entertains you with music during your meal.
The second option is only a short monorail ride away at the Contemporary resort.
Chef Mickey's is a really fun meal with Chef Mickey and his friends Minnie, Pluto, Goofy and Donald. This buffet restaurant also has a wide selection of food including a huge dessert bar. My family loves the fun atmosphere of this restaurant. Every now and then you will see a monorail glide by overhead and the character interaction has always been great when we dined here.
Both meals are a lot of fun, with good food and entertaining characters. I think the choice depends on which characters your children would be most interested in meeting. Enjoy whichever restaurant you choose!