Deborah:
Character dining at Disney is one of the best ways to get pictures of your toddler with characters without the excruciatingly long standby lines that are best avoided for children that age. But with that said, I would choose your restaurants based on the preferences of your 8-year-old. You didn't mention if your older child was a boy or girl, but regardless, they will remember this trip. Your one-year-old will only have the pictures.
With that in mind, universally,
Chef Mickey's is one of my children's favorite ways to see Mickey, Minnie, Pluto, Goofy and Donald but they love the vast array of food, too, especially for breakfast. If your 8-year-old is a girl, opt for Akershus over Cinderella's Royal Table for the princess interaction as well as the cheaper price. If you and your husband are not adventurous eaters, choose to go at breakfast instead of dinner but at least look at the menu before making your decision. If the story of Cinderella is a favorite in your house, consider 1900 Park Fare for its dinner buffet but also a chance to meet Prince Charming and the Wicked Step-sisters. Their humorous banter makes for good pictures with the baby but also your child might be chosen to dance with one of the characters. At 8-years-old, our children were the perfect age for character interaction: they had no problem hamming it up and hadn't gotten to the "too cool for school" age.
Besides character dining, our children always love to eat at 'Ohana for its all-you-can-eat shrimp and steak. Biergarten is another restaurant that always entertains and offers food that everyone enjoys. While you're at Animal Kingdom check out Rain Forest Cafe. It's tamer than T-Rex for your baby but the animatronics are fun for the whole family.
Wishing y'all a magical vacation!
Whitney