The level of planning is at your discretion. Having realistic expectations in my opinion is important. Too much planning may result in unrealistic expectations and schedules, while too little may result in you missing out on somethings and wasting time. As far as resort rooms it comes down to booking early to have greater availability of a resort, a resort room type or a special room discounts. Another dimension to this is the busy seasons of WDW which can also may specific resorts in higher demand than others (i.e. WL and PR are very popular during Christmas; Epcot Resort during Food & Wine). Christmas week at WDW produces the largest crowds of the year and is accompanied with the highest resort room rates. Wait lines are longer and table service at high demand restaurants book out 6 months out; others book out of the prime dining times. WDW is also driven by various other dates related to dining reservations, special tickets event availability and activities, Fast pass choices etc. It really helps to do the research...we have normally done 12 months out to get the discount rooms in limited supply, less than this and some resorts may be booked out on some room categories or booked out entirely, but still watch as a better deal can arise after you make your reservation that could derive from "Free Dining" announced at various times of the year, people cancelling reservations, rooms held for a conference are released, etc.
