In general, the week before and the week after Easter are the most crowded Spring Break weeks at WDW. When is Easter next year?
Of course, Spring Breaks are spread out all through March and April, so some people will avoid all of that block of time due to crowds. I think this past year both months were very busy due to the 4/3 special. Only time will tell how the economy is doing and what types of specials Disney runs.