We've gone the 3/2-3/9 last year and 3/1-3/8 the prior two years -- the parks are definitely manageable. The longest wait was at Dumbo (I have two small girls) for 30+ minutes. It tends to be far enough after the Presidant's week crowds and before the heavy spring break traffic.
We plan to go again this year around the same time. Definitley go -- the crowds will be fine.