Well, you could go for a beach week in Phuket or Langkawi, or as above Penang. Those should be good in "End of November, beginning of December". Avoid the Thai east coast islands like Ko Samui, which still could be in monsoon.
we are most interested in the historical types (temples, ruins, architecture, etc.)
So this sounds like Siem Reap might be another ideal place for you, with all of the Angkor ruins. There are higher end hotels with swimming pools there. A really good visit for Angor Wat takes 3 whole days, and there are side trips you can do to Tonle Wat (the biggest lake in Cambodia) and Battambang. But for Battambang, you'd want at least one night overnight there.
The last place is more of a puzzle. Chiang Mai might be a good place, or maybe Luang Prabang in Laos. But there's not enough for a whole week in either place. To make it a week, you have to use buses or private transport to go elswhere nearby. From Chiang Mai, you can make it a week if you join a trekking group to walk in the national park nearby, sleeping in the most basic rustic houses you can imagine. But that usually includes elephant rides, and some people object to that because they don't like to see elephants abused.
