We've been at WDW in March for several years now and have been lucky with weather and crowds. We're heading down 3/14 and praying for more of the same this trip!
Keep in mind though, Easter is 4/11, a week earlier than last year so I'm anticipating that it may be busier, as it's that much closer to the holiday.
Next year Easter is again in March, so we may wait until April. Did Easter week once, never again!!
Sheryl