VA Beach is awesome!
It probably will be too cold to do much swimming in March, but if you have a place to stay it should be cool. There are plenty of things to do--shows, little parks and other attractions. I'm sure that you can go to the city website to request information. Also there are lots of interesting historical things in the area (if that's your idea of spring break fun... I'm a history dork!
) like Colonial Williamsburg... also a big theme park there.