I was ther this March 20 to 26, the weather that week wasn't very good cloudy, windy and kind of cool. Pack some sweaters or jackets, nights can get very cool, 40s and 50s. We were told the temp the week before we arrived was around 80. Parks were not that crowded. March is when the spring breaks begin so you never know, that's why March is Magic and Premier season.
I'm going again next March also, will be there the week after you.
Lets hope for good weather and small crowds for those 2 weeks.