Thank you so much for the kind words and I’m always happy to hear that people find this information useful. As far as Turkey in December is concerned, I wouldn’t recommend it. I actually lived in a small town near Antalya on the Mediterranean for a bit over a year and I was surprised by the fact that almost everything closed down around 1-November and didn’t start opening again until March or April. Actually, I think Istanbul would still be enjoyable in December and so would Bodrum or any of the other larger cities including Antalya. But anywhere on the coast will be a ghost town and I’m pretty sure that Cappadocia would also be mostly shut for the winter. Ephesus probably stays open, but similar to Cappadocia, the attractions are all outdoors and they can get pretty fierce rainstorms in winter.
As December begins in the Caribbean, the hurricane season is officially over and the weather is pretty much perfect by any standard. Punta Cana is the Dominican Republic's most popular resort areas, especially for those who aren't particularly interested in absorbing the local culture. This is a resort area with wonderful beaches and not much history.
To the life aquatic now and Micronesia’s little-known islands scattered in the Pacific Ocean, which serve as the mating grounds for giant manta rays. With wingspans that can reach up to 5m, the chance to dive alongside these dancing behemoths shouldn’t be missed. From colossal to downright cute, rare (and ridiculously adorable) pygmy hippos can be found in Sierra Leone, once you've had your fill of lounging on palm-fringed beaches.
Needless to say, Australia is a huge country so you could spend 6 months there and not get bored, or you could spend one week there and barely see any of it. The obvious destinations are Sydney and Melbourne, both with plenty to do for non-beach people. Melbourne is known a bit more for culture and food, while Sydney is more pleasant and still very interesting. There is also the Great Ocean Road, which is a very scenic drive just a bit south of Melbourne.
If you’re a bit more on the timid side, you can always use Yelp and TripAdvisor to get good insights on places people have visited. As a disclaimer, some of the ratings may not be accurate on these sites, so make sure you go through and read some of the more recent reviews that people have written. We did this for a few of the places we visited and had no issues.
It’s going to be pretty cold in December all over Europe, although not quite so bad in the south, of course. As far as where to go, I’ll refer to our Europe 3-star traveler index, which lists every major city in Europe from cheapest to most expensive. The price is the typical daily expense per person for a couple traveling and staying in 3-star hotels. Once you scan through that list you should have some ideas.