In HongKong, where next for few days in Dec?

We will be visiting our daughter who is now living in HK over the xmas holiday week and would like to take her somewhere for 4 days Dec 30-Jan3. We are thinking Angkor Wat, Northern Vietnam or Lijiang or Beijing. Please help! Factors that enter in are ease of getting there, since my husband is very jet lag prone, and we are not arriving from the states til Dec 26, the limitations of our short time available, and to a lesser extent
the weather...( particularly if the highlight of the region is outdoor and active options - such as hiking and biking..). We are interested in all activities from touring historical sites, museums, and hiking and visiting local villages so are open travelers! Thank you in advance. Ps - do you have rec for reputable tour companies that you love for these places?