Another place I think is interesting too, in a different way:
Romania. Two years ago, saw a tour group going there, staying in haunted hotels, visiting scary places. I thought and still think it's quite fascinating, especially since I am quite a coward myself, ahahha. Would love to go if I have company.
Thinking of going to Beijing, Shanghai, Guangzhou and Shenzen during mid-Dec to late Dec. How's cold will these places be?
But the poster before was right. Under 25 you can get awesome deals all over Europe. I backpacked through Europe this past summer (Istanbul, Athens, Berlin, Prague, Vienna and Budapest) and saved a lot of money this way. Also helped since I had the international student card which gives you 50% (or more) off a lot of admissions. I got into Dolmabahce Palace in Istanbul for $2, compared to the regular price of $20.
If you can somehow con an ISC, it would help greatly.
My top to-go list changes all the time... but for now: