The last week in March at HH is usually a great time. We have been the last 2 years and have had a great time. The weather was exceptionally nice this year and warm & sunny last year. All of the resturants are open for the season and most of the resorts activies are in full swing. Signals (small rest.) and the snack/drink bar just opened for the season at the Beach House.
The ocean will be to cold to swim in although there are a lot of other beach activites to enjoy like bicycling, horesback riding, sandcastles, shelling, tanning, ect..
I would recommend this time of year.