Rather than sending out an email that was sure to get lost in everyone's inbox, we created a special invite to be mailed to each employee's home.
We wanted this invitation to stand out, but not to be too "out there" design-wise since it was for a corporate event.
I think this design really hit the nail on the head as far as design goes. It does not have waves, beach umbrellas, or sea shells, but still communicates "beach trip."