Craig,
Thanks for your question to planDisney!
My family has been staying at
Disney's Grand Floridian Resort & Spa since my girls were that age, so I think I can help out!
Let's start with your dining question. At the Grand Floridian is one of my kids favorite dinner destinations to this day.
1900 Park Fare, if it has reopened, has a great selection for palettes of different ages, and the character interaction is quite good. At dinner you are hosted by Cinderella and friends. The
Grand Floridian Cafe is there too, and certainly would accommodate your family. It may not have the entertainment draw of other restaurants, but it offers a menu with some variety and a quieter setting after a long day at the parks.
Just a walk away at
Disney's Polynesian Village Resort is
'Ohana, which is likely my top recommendation of all the restaurants I list in this answer. The food is great, and the views of the
Magic Kingdom Park as the evening sets are even better.
Kona Cafe is also a family-friendly destination. In both cases you get a great meal, and a chance for the kids to explore the well themed island atmosphere of the resort.
The final Monorail resort is
Disney's Contemporary Resort, with one very-kid friendly destination in
Chef Mickey's. With Mickey Mouse and friends as hosts, you can imagine that they are ready for the youngest of guests. There is also the
California Grill and
Steakhouse 71 at this resort. Neither are what you would call a child-oriented restaurant, but if you want something a bit on the high end our kids enjoyed going to California Grill when they were 3 and 5, and it is my wife's favorite. You can gauge if your kids are up for something like that or not.
Please note that all these resorts also have quick service dining options, which can sometimes be all you want, or need. The one in the Grand Floridian is the Gasparilla Island Grill.
As you can read from the dining review, the monorail resorts are the Grand Floridian, the Polynesian, and the Contemporary. You can also access Fort Wilderness and
Disney's Wilderness Lodge via boat, though in both cases you have to transfer from the boat that takes you to the dock in front of the Magic Kingdom to another boat that takes you from there. That first boat ride sometimes loops from the Magic Kingdom stop to the Grand Floridian and the Polynesian, but walking over is easier and faster.
I hope that this helps? Write me back if you have any other questions!
Have a Magical Vacation!
Doug