Warm weather, Caribbean beaches, and fascinating history beckon visitors to this coastal city during December. Once a 16th-century Spanish port, Old Town Cartagena, surrounded by ancient stone walls, is a UNESCO World Heritage site. Visitors strolling through its streets will see original Spanish Colonial architecture among new restaurants, restored homes, and boutique inns. From street food to upscale restaurants, Cartagena offers the best in local seafood, meat, and fresh fruits. In December, the city becomes a festival of lights, with nativity scenes, decorations, and holiday celebrations culminating with New Year’s Eve fireworks. Holiday shoppers will want to take home gifts of colorful handcrafts sold at markets throughout the city, with special Christmas markets arriving in December. Colombia supplies nearly 90 percent of the world’s emeralds, and a quality gem from a reliable source would make a memorable keepsake. Nearby Rafael Nunez International Airport makes arriving by air quite convenient, and visitors will find a range of lodging in and around Cartagena. For a luxurious vacation, the new Conrad Cartagena offers four pools, a private beach club, a golf course, seven restaurants, tennis courts, a spa, and stunning ocean views from every room.
If you are looking for a cheap, beautiful, and relaxing beach destination during December then Goa is ideal. This has become hugely popular with package tourists from Europe and Israel (and more recently Russia), and the facts that pretty much everyone speaks English and there aren't many cultural opportunities means that it's a perfect place to just vegetate in a beach chair for a week or two.
Southeast Asia is easier to deal with, and there are cheap flights connecting in the Middle East and landing in Bangkok, Kuala Lumpur, and Singapore. Each of those is a very interesting city, and there are many smaller places to go in the same region. In Malaysia there is Penang and Melaka. In Thailand there is Chiang Mai and quite a few others in that area. In Laos you can visit Luang Prabang, which sounds like it could be a winner for you. And there is also Siem Reap, which is home to the amazing Angkor Wat temple complex.