Very exciting stuff! There appear to be quite a few Character Dining options at the various parks. Most are at Disney, including several princess ones--Cinderella's Castle, Cinderella's Happily Ever After Dinner at 1900 Park Fare, My Perfect Princess Tea Party at 1900 Park Fare, as well as the one in Epcot that was already mentioned. There's also a Wonderland Tea (which I believe is free?) at 1900 Park Fare.
However, I have read that there is also a Character Dining at Universal Studios that features Spiderman. I have no idea whether or not it a good interaction and/or meal, but something to consider!
From what I understand, booking ahead of time is key for character dining (upwards of 180 days is recommended), but even if you are short on time, give them a call. You never know when a last-minute cancellation will open up!
Best of luck!