Hi, Jessica!
Two character meals would truly make your 4-year old's trip (and, maybe, yours, too!) While I don't know if your little one is a boy or a girl, I'll suggest those which appeal to everyone. (IF, however, your little one would like to
dine with a princess or
dine with Jake the Neverland Pirate, there are other locations you may want to try!
Character Dining options abound throughout Walt Disney World; you really can't go wrong with any one of them. Otherwise, don't miss Chef Mickey's at Disney's Contemporary Resort or Winnie the Pooh and Friends at The Crystal Palace at Magic Kingdom, both of which are great buffets...with character! 'Ohana is a family character favorite, as is 1900 Park Fare, both of which include characters that will make your meal that much more magical!
For Quick-Service DO NOT MISS Wolfgang Puck Express at Downtown Disney's Marketplace (not to be confused with her sister Wolfgang Puck Cafe.) This is hands-down THE best QS restaurant on property. The menu is fantastic, the service is wonderful, and everything is made to order, then delivered to your table...all for the cost of a QS meal. Truly fantastic. Another great QS location is Sunshine Seasons, at The Land Pavilion at Epcot. The lunch / dinner entrees are spectacular for a QS, and the dessert options will surely impress you, too. Yum.
Send another question including your child's interests, and if Mom and Dad have any particular dining interests when celebrating this VERY special occasion...your honeymoon! I'll help set you up with the perfect locations for every meal...promise! :-)