Hi Mark! Welcome to the Disney Parks Moms Panel! Thank you for bringing your question to us.
You are right that advanced dining reservations are a great idea. To keep it simple, I will give you our very favorite choice at each park.
Magic Kingdom: Be Our Guest Restaurant-- This is the newest restaurant at the Magic Kingdom and is in high demand. If you choose this, be sure to be ready to book your reservation at the 180-day mark before your trip.
Epcot: Via Napoli ---This was a tough call because there are so many great choices at Epcot. But, with your kids being little, pizza is usually a big hit, and this pizza is delicious!
Animal Kingdom: Donald's Safari Breakfast -- This is my family's MUST-DO on every trip. The food is delicious and the characters are so much fun.
Hollywood Studios: 50's Prime Time Cafe -- You will feel like you have stepped into your grandmother's kitchen, and the servers are amazing!
All of these recommendations are "table-service" restaurants. There are also "quick-service" locations at each park that you wouldn't need reservations for.
Here is a link to some Frequently Asked Questions about dining reservations at Walt Disney World.
I hope some of these suggestions sound good to you. Have a great time planning and a very magical vacation!