You would probably get some rain in Cartagena in November, but mostly in the first half of the month, and even then it tends to come down in short bursts rather than all day, so it’s usually easy to avoid. I love Cartagena for trips like this because the walled historic part of the city is really lovely and fun, with plenty to see and do. The nearby beaches are big, but the sand isn’t white and fluffy, so they won’t make too many “best beaches” lists. It’s also very cheap there, and especially at the tail end of the off season like that. As long as you don’t mind the possibility of a couple of quick rain storms, it should be great.
Sri Lanka could also be great, and it’s very different. In fact, you might even consider a trip to India itself, which is obviously similar to Sri Lanka. But Sri Lanka is far easier to do in about 12 days, with most of your time spent in the mountains and a bit along the southern coast. Colombo is mainly just good for flying in and getting your bearings. Sri Lanka is also a bit more expensive than Vietnam, but both are great value. And again, you could instead go to Kerala and Goa in India on a short trip, although those are more about relaxation than culture. Let me know if you have any other questions, and I hope this helps. -Roger
My favorite part of Bali is now the area around Lovina along the north coast, which is still very mellow and mostly open spaces with light development. It’s really beautiful and there is plenty to do. You can get similar experiences by visiting the nearby Gili islands, which also feel like Bali used to be 20 years ago when it was much nicer. They are all really beautiful and relaxing islands with great scenery and very friendly people. You just need to steer clear of the places that are the most crowded.
The rainy season usually ends early in November in Siem Reap, and the tail end of it is rarely fierce, so this is an ideal month to hang out in town and spend multiple days at Angkor Wat. November is actually the coolest month of the year, by just a bit, at least during the days, so most people will appreciate more moderate temperatures when climbing up and over all the temples.
Since flights to Mexico City from the US and Canada are usually quite cheap this time of year as well, this could be a perfect short cultural holiday. This city has great shopping, dining, and nightlife, and the central historic and tourist districts are far safer than most people would expect. There are ruins just out of town as well, so a bit of everything is available.