Hi Farrah,
Thanks for visiting the Disney Parks Moms Panel with your question. Character dining is a great way to meet and interact with characters without standing in line. There are many fun options for your three or four-year-old to meet Mickey Mouse or Minnie Mouse for dining. You should know that characters who appear at meals are subject to change at any time.
A great option where you are likely to meet both Mickey Mouse and Minnie Mouse is
Chef Mickey's at Disney's Contemporary Resort. This is a buffet meal for breakfast and dinner where the characters appear in chef outfits. Another option is Cape May Cafe at Disney's Beach Club Resort. At Cape May Cafe, the characters appear in outfits that look like they are heading for a day at the beach. This is again a buffet available for breakfast and dinner. It is typical that you may find Minnie Mouse at Cape May Cafe; however, Mickey Mouse is not listed as appearing here. You may also find Mickey Mouse at 'Ohana at Disney's Polynesian Resort for breakfast, where he would be wearing a flowered shirt.
If you are interested in dining inside of a theme park and trying some unique fare, you can try Tusker House Restaurant at Disney's Animal Kingdom. Tusker House offers character dining at breakfast and lunch, and Mickey Mouse may be one of the characters who appear. At this meal, the characters appear in their safari outfits.
Whichever option you chose for your character meal, Farrah, be sure to make reservations as early as you can either online or by calling 407-WDW-DINE (407-939-3463). Character meals are popular and fill up quickly. Whichever you chose, I'm sure you'll have a wonderful meal!