Hi Leeann! Welcome back to the Disney Parks Moms Panel! A good rule of thumb for you to use is for any restaurant that accepts reservations - make them! You can start making reservations 180 days prior to your arrival date at Walt Disney World which I highly recommend. The more popular restaurants and times will book to capacity.
As far as which
dining reservations to make, you can't go wrong with any of the character meals and if your girls love the princesses, that is a great place to start! Of course, breakfast in Cinderella Castle is always a treat and if you have trouble getting that reservation, you can try Akershus Royal Banquet Hall or 1900 Park Fare for dinner. Your girls are welcome to wear a princess dress which will make your pictures that much more fun!
One of my other favorite character dining locations is at Crystal Palace in Magic Kingdom. Who wouldn't want to dine with Pooh Bear & friends? If possible, try and get a reservation on or before 8:30 on a day when the park opens at 9:00. You'll be able to stroll down Main Street U.S.A. and feel like you have the park to yourself. It's also a great time to get an excellent picture in front of Cinderella Castle!
Chef Mickey's is another must-do and if your girls love Disney Junior, be sure to check out Hollywood & Vine at Hollywood Studios!
As you can tell from the link above, there are so many dining options but not enough time to enjoy them all. I suggest clicking on the link and use the filters located on top of the page to help narrow down your search. If you have any additional questions, you know where to find us!
Leeann, I hope your Walt Disney World vacation is truly magical and full of pixie dust!