We use the waltdisneyworld.com website to pre-plan all of our trip. Actually now they have updated the website (recently) so that you can book your dining reservations online rather than calling back to Orlando.
If you pre-plan all of your options (maybe 2 or 3 options with some backups to avoid calling back at another time) it will save you the $ in calling back a second or third time and gives you a better idea of the prices of your trip.
Hope that helps!