Just one idea: if you're going to Croatia and have the time, do visit some other countries in the region as well as the distances are relatively short.

If you want to save money, inexpensive bus services cover most of the area. You could also look into e.g. Adria Airways' and Croatia Airlines' websites for cheap fares between the cities in the area. I think Belgrad, Ljubljana, Sarajevo and Ohrid (Macedonia) are all nice cities in that area. If you go to Macedonia, you can easily visit Kosovo and Albania as well - if you're interested in collecting passport stamps that is.

Somebody mentioned Hong Kong. Well, people don't usually visit Macau but I'd recommend it for short trip. You can get the Chinese visa in 24h there as well, and catch a bus to Guangzhou from the border.