The rainy season in Belize doesn’t really end until early January, which is why it didn’t make the December list. Belize is definitely affordable enough to make this list and it appears for many of the following months. If you are thinking about going to Belize in December I think it’s a good choice. As you probably know, the Tropical rain patterns are such that the showers tend to come and go quickly, and they are often overnight. -Roger
Another reason to consider Dubai is that the busy airport has cheap non-stop flights coming in from almost every major airport in Europe and Asia. As a result it's popular to book long weekend trips of 3 or 4 days to Dubai, where you can enjoy some sunshine and shopping before flying back home where it gets colder by the day. You might also consider stopping for a few days in Dubai and then moving onto somewhere else with cheap direct flights such as the Maldives.
I’m happy to try to help. It’s hard to say whether one 30-day trip would be better than several shorter trips. On one hand, it’s much more efficient to go for a month because it obviously saves you all the going back and forth. Also, one week is a short time to go 7 or 8 time zones away, as it takes pretty much an entire day each way, and at least a few days to adjust to the time change. Hmmm…
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.