November-Feb is high season for SE Asia. With two weeks at a time I think I would probably pick a country or two to focus my time on.

If you have not been to Thailand you could easily spend 2 weeks there. Getting around is easy. Luxury hotels are relatively well-priced. Bangkok has a glut of top class hotels so rooms are plentiful. In addition to Bangkok a nice trip includes some time up in and around Chiang Mai for a different pace and to see a very different side of Thailand. And there are plenty of beach destinations.

The rest of mainland SE Asia are also favorites of mine. You could go to Myanmar before it changes even more. But there is little luxury to be found and the infrastructure is still pretty weak. If you have not been to Cambodia I would probably go ahead and see Angkor now. It is pretty overrun with tourists but that is not going to change. You could combine Cambodia with a visit to Laos, another pretty sleepy country.

I did not love Vietnam when I was there a couple of years ago. There are definitely some interesting places to visit but the whole place felt like a giant construction site to me.

I suppose a lot depends on what sorts of things you like to do. If all you want to do is lounge at the beach then that would probably steer you one way. If you want to see a lot of historic sites, temples, etc then that would be a different direction.

I don't think Brunei is an "obvious" destination by any means. I have not been there. The impression I have is that there's not much to it. So it could be off the path a bit.

I am headed to Taiwan for a week this Nov. I didn't know much about it when I booked and after I started doing more researched I wished I had set aside more than a week there as the island seems to have lots of different personalities and worthwhile places to go. So you might want to go there. Not sure they have much in the way of beaches. Seems to be more of a place for nature (in the mountains) and some historic cities.