Hi Shannon!
I think that's a great suggestion! I have two sons, and their favorite birthday experiences have been Character Dining experiences.
We've really enjoyed Chef Mickey's at the Contemporary Resort, Breakfast with Lilo & Stitch at "Ohana at the Polynesian Resort, The Garden Grill at the Land Pavilion in EPCOT, and breakfast with Goofy & friends at Cape May Cafe at Disney's Beach Club Resort. Click on this link for more information:
Character Dining Experiences.
Also, check out ways here to
Customize Your Celebration! You can find everything from special hats, in-room celebration gifts, and recognition buttons, to celebratory cakes that you could order for your special Character Dining Experience.
Most of the Table Service (& Character Dining) restaurants will allow you to pre-order a special birthday cake by calling ahead at least 48 hours before your Advanced Dining Reservation. Call (407) 827-2253 to place your order.
I hope this is helpful to you as you design a special celebration for your three sons! Have a magical time in Walt Disney World!