Stephanie:
I think you'll find the weather just about perfect in late February and early March: shorts in the day and sweatpants or jeans in the evening. I recommend that you take a light jacket to wear if you plan on arriving in the parks early in the morning, but you can tie it around your waist as the afternoon warms so you can bring it out again in the evening. Weather is unpredictable in the non-summer months, so make sure to check the forecast for spikes on either end of the temperature spectrum. Also, pack a poncho as I've encountered rain just as often in cold months as the afternoon showers in the hot months.
Crowds begin to build going into March as many schools begin to let out for Spring Break, but your week will fall nicely between President's Day and the first wave of Spring Breakers. You certainly won't see crowds like Christmas but you won't experience lulls like September either. Disney is open 365 days a year and while some attractions may be closed for refurbishment in the early weeks of the year when crowds are low, Epcot will hold
Illuminations nightly at 9 p.m. while Magic Kingdom and Hollywood Studios will have their own nightly entertainment, albeit not every night. Make sure and keep an eye on the
park calendar closer to 90 days from arrival to see the schedule for
Fantasmic! at DHS and the parade and fireworks at Magic Kingdom.
Wishing y'all a magical vacation!
Whitney