March is by far the best month for snow fall and not so cold temps as linville said. Plus at that time of year everything should be open at the resorts. Given a normal season and all. Spring Breakers would definitely be a presence at Winterpark. During the week though, traffic is much less.
April can be really good too. Crowds are much less and storms still roll in. When the storms aren't there it's generally sunny and things soften up to nice corn riding. The only draw back is that is the time of year that you get those windy overcast days that just leave frozen crud for a snow sliding surface. This is the only time I don't care to be out riding anywhere. It just sucks.