We stayed at the Poly last November. We just returned Wednesday from AoA Cars Suite. The suite was spacious and we loved the various themes. However, I would have preferred to have stayed at the Poly again. I love the resort, the rooms are large and you can't beat the location. However, the price difference for the 6 nights we were there was $1,000. I would definitely say that the the extra $110 you would be paying is well worth it. The Poly is a beautiful resort and feels like a vacation within a vacation. Your kids will love the monorail and the boat to/from MK. They'll also love the volcano pool and being able to see Cinderella's castle from the pool.
I have two sons and we had character meals at Crystal Palace, Chef Mickey's, 1900 Park Fare and Tusker House. Last trip, we also ate at the 'Ohana breakfast. My kids love the character meals. Crystal Palace, 1900 Park Fare and 'Ohana were the best of those meals. Since you have girls and you're only eating at one character meal, I think 1900 Park Fare may be the best choice. What's also nice is that the characters there can speak so they can interact even better with your children. My DS told Mad Hatter that it was his "Un-Birthday." He replied, "it's my "Un-Birthday" too. Mary Poppins told my kids that they have very good manners.
If you decide to not do a character meal, 'Ohana's dinner is one of the best meals we have had on property. We went last year for the first time and returned again this past week. We had excellent service and the food was delicious. Kona Cafe is also very good.