In Asia, I would go to Cambodia (esp. the Angkor temple complex), Thailand,
Indonesia (Bali and Central Java, around Yogyakarta), Nepal, and the “Golden Triangle” of India. Maybe also Sri Lanka and Myanmar, especially Bagan and the lake. I haven’t been to Bhutan, but I suspect that would be on my list too.
However, regarding China, unless you have traveled very extensively there, there is a ton to see there. Tibet would be very high on my list of Asian destinations if you haven’t been there, and also Yunnan province in southwest China — those are areas that don’t tend to get a lot of foreign tourists. Lots more in China too, which is more like a continent than a country.