I think it's a great idea! You can package it however you want to -- cellophane bags, tulle circles, little brown paper bags (maybe stamped with a seashell or starfish or something beachy), favor box.....
Salt water taffy is a great favor for a beach wedding. I'm partial to cello bags, but you can really package them any way that appeals to you. Try Papermart.com for lots of packaging options.
Re: Yay or Nay? Beach Wedding Favor