Our dd (now almost 5) has been there a few times and absolutely LOVES Chef Mickey's. It wouldn't even be a complete trip for her without it. We do dinner on opening night to get us in the Disney mood.
We did the castle for breakfast and she did like but said she didn't want to do it again. She likes the classic characters better than princesses. she tends to be shy with the "real" talking Princesses

I honestly think the castle is worth it if your girls are totally into it. If not, maybe just Norway breakfast or 1900 Park Fare. I wouldn't do all character meals though, the food gets redundant and there are some really nice restaurants in WDW. Most will keep little ones busy but here are some of our other favs...
Ohana's which has great food and a fun atmosphere. Hula hoops for the kids, coconut races.
I would also recommend Coral Reef. Not only do you try good seafood but the girls will be happy watching the tanks of fish.
We did 50's Prime Time and she liked it in there and LOVED Daddy getting yelled out by the waitress about elbows on the table, the waitress also spoon fed him his green beans. She was belly laughing.
We are trying WCC and Sci-Fi this coming trip which I think she will like.
I would still try places YOU might like though like LeCellier (yum!) since most servers are so great with the kids, the get crayons and such. We always play games like "funnies moment today, best ride today" and we also do I Spy. Just make sure your kids are well rested and not exhausted when doing a meal and they should be fine.
HTH