I’ll be happy to try to help, but I’d really need to know your starting point because there are cheap places in different corners of the world, and it’s not worth flying halfway around the world to try to save US$20 per day. In mid December through January for beaches you should consider Thailand and perhaps also Vietnam. I’ll give you more information once I know where you are starting from. -Roger
The largest national park south of Alaska, Death Valley is located 295 miles northeast of Los Angeles and 120 miles northwest of Las Vegas. Much of the park is below sea level, and it is surrounded by mountain peaks, often covered in snow. December’s temperatures are moderate, generally in the mid-60s during the day and 40s at night. Daily guided walks and naturalist talks are presented by the National Park Service, acquainting visitors with the natural beauty, history, geology, and wildlife of the area. Stargazers will be in awe of the Milky Way and starry nighttime skies of this “Gold Tier” Dark Sky Park, a designation by the International Dark Sky Association. The newly renovated Oasis at Death Valley (formerly Furnace Creek), hosts the elegant 4-diamond Inn at Death Valley and the family-oriented Ranch at Death Valley, offering visitors a range of lodging options and activities. At Furnace Creek Stables, guests can explore the valley floor or foothills of the Funeral Mountains on guided horseback rides. The Stables also offer carriage and hay wagon rides. Jeep rentals, tours, and a variety of hiking and walking paths provide many ways to experience Death Valley. Play golf at the world’s lowest elevation golf course or enjoy a rejuvenating spa treatment at The Inn.
I think Sri Lanka would be wonderful for 2 weeks in December. The rainy season typically ends early in December, but even when it’s still going it tends to be quick downpours, as you are no doubt familiar with if you’ve been all over southeast Asia. Still at this point there are very few hostels with dorm beds and not even many cheap budget hotels, but at the age of 30 you are probably happier with normal hotels anyway. Value is quite good in Sri Lanka as long as you can spend at least US$30 or so per night, and hopefully a bit more. Food is also quite cheap in general, although there are still surprisingly few tourist-oriented restaurants in many towns so it feels a bit undiscovered. Just don’t spend much time in Colombo and preferably focus on the mountain areas, and I think you’ll love it.
If you have a flexible schedule, or if you just happen to have some time off in November, you are in luck. This is honestly the best month of the year for finding cheap destinations that also have fantastic weather. Since most people don't start their winter travel until mid or late December, it means crowds are small and hotel prices are low through huge sections of the travel world. Those wondering where to go on holiday in November have many great choices at bargain prices, although airfare may cost a bit.