Hello, Kimberly,
Since you will be visiting the Magic Kingdom for one day, I think it will be best to try and epitomize your Disney experience as best as possible while selecting a restaurant that uses one table service dining entitlement. My first immediate thought is
Be Our Guest, which is a magical experience that lets guests experience the beauty and mystery of Beast's castle. And of course, you can even try the grey stuff (it is delicious!).
If you are willing to take a short break and leave the Magic Kingdom for dinner, there are some popular spots at the nearby Magic Kingdom resorts (a monorail or boat will take you to these resorts). At Disney's Polynesian Village,
'Ohana has been popular spot with guests for many years as Hawiaan-styled dinners are served family style. If you'd prefer a little more spirit and entertainment from the Great West,
Whispering Canyon Cafe at Disney's Wilderness Lodge has chuck wagon favorites and lots of fun antics that you can watch from the sides or participate in. Little ones can even race wooden ponies!
If you'd prefer relaxed, yet elegant dining, the
Grand Floridian Cafe is at Disney's Grand Floridian. You'll have a chance to visit Disney's flagship resort and have a lovely dining experience, but you certainly won't feel out of place taking a break from a day spent at the Magic Kingdom.
Please know that these restaurants are quite popular, so I would try to make your reservations 180 days in advance.
Happy dining!
-Kara