As with most on this list, hotels get very full and more expensive just before the Christmas holidays, so it's better to come early in the month if possible. That way you'll have your pick of places at some surprisingly good room rates, even at some high-end places on the famous beaches. If you are coming during Christmas then book a hotel NOW because they'll be full and will keep getting more expensive the longer you wait.
If you are looking for an all-inclusive resort with reasonable airfares from Chicagoland, your best bets will be in Punta Cana, Dominican Republic, or the Cancun/Playa del Carmen area. Both have everything on your list, except perhaps wild life, depending on how you define that. You can get cheaper flights into Cancun, and there is a wide variety of offerings once you are there. If you don’t think you want to leave the hotel much, then stay in the Cancun hotel district or along the Maya Riviera nearby. But if you want to interact with a real and lovely town, then stay in Playa del Carmen or over on Cozumel. There are many nearby activities and some very interesting ruins.
If you are looking for a place to go abroad for a few months starting in early December, you are right on the money with Thailand as the best starting location. The weather is really nice that time of year, and it’s quite easy to keep things extremely cheap if you need to. Many of us in the travel writing community have spent months or years traveling around southeast Asia, and I’ve probably spent close to two years there myself. Bangkok is the obvious place to start and it’s an amazing city. After that you can either go north to Chiang Mai and Chiang Rai and then over to Laos, or you can head south to one or more of the islands. Cambodia has a lot to offer, and especially in Siem Reap, and Vietnam can be entertaining for all three months of your first visa there.
For traditional holiday atmosphere, think about Rome or Vienna, with Christmas markets, nativity scenes, and decorated cathedrals. In Edinburgh, they know how to welcome the new year with several days of celebrations culminating in New Year’s Eve. For travelers seeking a wintery destination, Tromso in Norway has skiing, reindeer, and a chance to see the Northern Lights. Bundle up for a dogsled tour or join a whale watching excursion.
December is a fun time to be in Rajasthan (though a busy one—this is peak season). The weather is cooler—something to relish, as it means long explorations into the bazaars, wonderful walks around the forts, and a chance to explore the villages on foot without overheating. Evenings are spent wrapped in beautifully decorated Rajasthani shawls and blankets as you dine outside by firelight. The winter light is beautiful, particularly in the villages, making this an ideal time for any travelers with a passion for photography.
Fortunately, Bangkok remains very cheap by almost anyone's standards. If you want to splash down for a nice 3-star room then it'll be half the price of a similar room in Europe or the US, and if you are fine with something more basic then you can find a room for next to nothing, even in the fun Khaosan Road backpacker district. Street meals for around a dollar are always there too, so you'll be able to afford a bit more for a room anyway.
Actually, most of the popular European cities have fairly mild winters, in that they don’t spend much time below freezing and snowstorms are rare as well. It’s hard to make suggestions without knowing about your tastes, but I will tell you that the most popular European cities are London, Paris, and Rome, and none of them get snowed in often. If you are going to Italy, you should also go to Florence and maybe Venice as well.
Oh, and I just noticed you asked about general safety as well. Buenos Aires is fine as long as you don’t wander into the bad neighborhoods after dark, which is pretty much true almost anywhere you go, including Europe. But Rio is sadly famous for petty crime and it’s a real issue. As long as you know what NOT to do it’s quite safe, so I’ll still recommend it as long as you read up a bit on the topic. The most common problem is when people walk down to the water on the beach after dark. As long as you know NOT to do that you should be fine, but if you did go for an evening walk near the water and out of sight of the well-lit sidewalks, the chances of getting mugged are extremely high. Again, it’s worth learning about it and it’s easy to stay safe if you do. Let me know if you have any other questions. -Roger
Sri Lanka could also be great, and it’s very different. In fact, you might even consider a trip to India itself, which is obviously similar to Sri Lanka. But Sri Lanka is far easier to do in about 12 days, with most of your time spent in the mountains and a bit along the southern coast. Colombo is mainly just good for flying in and getting your bearings. Sri Lanka is also a bit more expensive than Vietnam, but both are great value. And again, you could instead go to Kerala and Goa in India on a short trip, although those are more about relaxation than culture. Let me know if you have any other questions, and I hope this helps. -Roger
The rainy season is still finishing during November in Central America, but a bit north and south of that it's dry enough to make visiting very worthwhile. Better yet, it's still low season for hotels in most places even though the weather has gotten nice. Latin America is filled with excellent bargain choices and it has some of the best places to visit in November.
In November you can find excellent resort deals all over the Dominican Republic, but Punta Cana is typically the first choice, especially if you are looking for an all-inclusive resort with all the luxury extras at a great price. The resort is actually a collection of little beach areas on the eastern tip of the island, so it's very secluded and well away from some of the confusion closer to the capital city.
Traveling during the last ten days of December means crowds and exorbitant prices throughout much of the world, but the first two-thirds of the month—before holiday airfares and hotel rates go into effect—can be a serene, value-laden, and just plain lovely time to vacation. Europe is all decked out for the holidays—with locals generally friendly and in high spirits; in the Southern Hemisphere, spring is in bloom; and in the Caribbean, Hawaii, and Mexico, hurricane season is over, the weather is gorgeous, and there are free upgrades galore.