Plan your perfect trip to the Caribbean with this three-for-free promotion by the St. Kitts Marriott Resort & The Royal Beach Casino. Book four nights at the regular rate (from $169 a night) and you'll get three additional nights for free, which breaks down to $96 per night for a seven-night stay. Just book by Dec. 31, 2015 and use promo code ZJL. (From: 22 Vacations Under $100/Night)