Hello -- two families with young children are venturing down to Florida for Spring Break 2012 and need to decide on a place to stay for the week. We have been to Captiva and loved it, but have never seen Key West or Marco Island. We fell in love with Captiva's charm, clean, white sandy beaches. We love shelling, parasailing, swimming in the ocean/gulf, quiet/quaint streets, etc. Which of the three is better???