I'd recommend going to one of the monorail resorts, as most of the TS restaurants in the MK get booked fast. If you really want to stay in the MK, you may want to try the Plaza, which a lot of people overlook. I have that booked for lunch during my November trip and I have only heard good things about it.

As for the monorail resorts, The Wave at the CR is the most convenient monorail resort TS restaurant and probably will have the best availability for dinner. It has good food and it's relatively quiet, so you can really have a relaxing meal there. Then I'd try the GF Cafe or Citricos or Narcoossee's. The GF has five (5) TS restaurants, so that resort can have restaurants with good availability. Many of the other monorail resort TS restaurants ('Ohana, Kona, 1900 Park Fare, Cali Grille and Chef Mickey's) do get booked up quickly.

Good luck.