As the PP said, Fantasy Faire is really composed of two things: the performance and the meet and greets. If you children are not interested in the princesses, then I would probably forgo the meet and greets. The show (more like a skit) can be fun, so that might be something to consider. Personally, with all the other fun things to do and see at DLR, I would probably forgo Fantasy Faire if your kids aren't into the princesses, unless they like watching shows and are a fan of either Tangled or Beauty and the Beast.
Also, as the PP mentioned, even if they aren't into the princesses, there are some yummy snacks at Maurice's Treats. There is the frozen apple juice (I'm not a huge fan, but I'm not a big fan of apple juice to start with). I do like the baked twists (strawberry was my favorite) that they sell.