Many restaurants back in June were turning away people without reservations. The previous poster noted that President's weekend is very busy so you should make at least some ADR's. Try looking over the menus on allearsnet.com for ideas. One thing we have learned over the years is not to make a dining reservation far from where you will be at that day and time. For example, don't plan on eating at any restaurant in the Disney Studios if you plan on being in the Magic Kingdom for that day or that part of the day. Make your dining plans go along with whatever theme park you will be visiting at the time. Also consider the resorts close the that theme park. From the Magic Kingdom you can easily get to the Contemporary, Grand Floridan, or Polynesian.....ps Kona Cafe at the Poly is GREAT!.
From Epcot or the Studios you can easily get to the Boardwalk, Beach and Yacht Clubs, and Swan and Dolphin.
Happy planning and keep reading these boards for great ideas.