Hi Tiffany,
What a lovely idea to have some character meals, my family loves them because not only do we get to have a nice air conditioned rest and delicious food but my girls can meet their favourite characters without having to queue!
If you're thinking of price then breakfast will almost always be cheaper than lunch or dinner, but although it's cheaper you need to consider if your family will eat enough breakfast type foods to get your moneys worth. I personally like to book a late lunch as we are then all really hungry and also ready for a break from touring the parks.
The Princesses can be found at 3 dining locations at WDW, firstly the most popular and most expensive is Cinderella's Royal Table in the Magic Kingdom, you get to eat in the Castle so it is gorgeous. Then there is Akershus Royal Banquet in Epcot and 1900 Park Fare in the Grand Floridian, my recommendation would be Akershus for both price and characters. What I suggest you do is have a look at the dining pages on
www.allears.net if you look to the left hand side there is a link for character meals, this will show you all the Disney World has to offer and the menus and prices for each restaurant!
For your son it really depends on which characters are his favourite, a few of my families favourites are the Crystal Palace in the Magic Kingdom with Winnie the Pooh and friends, breakfast at 'Ohana with Lilo & Stitch and Garden Grill at Epcot with Chip & dale and friends.
When you've decided make sure to call dining on 407-939-3463 up to 90 days in advance to make your reservations.
If you have any follow up questions I'd be happy to help,
Jo