I am going to Thailand (mainly going to Koh Sumai probably which is a beach resort island), Tokyo, Hong Kong + Macau, Seoul, Australia, and perhaps China for a year.
Going with my best friend.
Ok, I've done that trip as well and I highly recommend signing up for scuba diving while in Sumai which will take you over to a nearby island called Koh Tao and the first dive spot should be Mango Bay, a place where its beauty transcends what your photo will capture. At least when I went back in 2007 it was. Bring 500 bucks to Thailand and you'll feel like a king, money goes so far there.
Tokyo is amazing for a culinary adventure. I did everything from eating at cheap ramen stands to lucking myself into Jiro's for sushi and tracked down authentic Kobe steak which even in Tokyo is difficult to find (you'll see wagyu all over but Kobe is the best cut of wagyu). Those two meals were 300+ bucks each for just myself so you have a wide berth of amazing options depending on what your budget is. Before people laugh at what I spent for those two meals I'm a foodie so I view them as experiences.
Seoul, track down a Jjimjilbang which is basically a bath house/sauna but the one I went to there had three rooms: a cold room, a hot room and a "hot hot" room. You bounce between them to shock the senses but it feels great and is worth tracking down. Baseball is pretty entertaining there, they have a cheer leader group and some guy that goes nuts to get the crowd going. Their team is the Duhong Bears or something like that. Although I just realized that won't be going on this time of year.
Where are you going in Australia? I'm assuming Sydney, Melbourne, probably Cairns to check out the Great Barrier Reef? If you go up to Cairns, swing over to the Golden Coast (string of 30 beaches along the Eastern shore) and take the train to the Zorbing location. You can google Zorbing but anyway I did that with a buddy and it was so damn fun.
I haven't been to China but in any case I could talk about travel pretty much all day so if you want any recommendations for any of the countries I touched on or have questions shoot me a PM.