It's rumored that Disney is going to go back to allowing guests to make dining reservations 180 days prior to their arrival. It's currently 90 days. This is good except for those booking last minute trips. And there is a pretty big trend going on right now where people are booking just a few months out.
There are so many restaurant choices in Disney that you really have to research them and check out their menus. http://disneyworld.disney.go.com/restaurants
Some reservations are difficult to get even at 180 days out. LeCellier, Yachtsman Steakhouse, dining with the princesses in the castle and Victoria and Alberts are just a few.
If you've booked your trip and are making dining reservations either online or via the phone, make sure you have your Disney vacation reservation number because they will need this to book your dining.