I just found out that I have 2 weeks off to travel in mid-July, and I would like to go to Asia. I've never been there before, but will go with a friend. Are there any necessary vaccinations that we should get ASAP? What are the best countries to visit? Am I limited to countries that do not require a visa, such as Thailand, Hong Kong, Japan, and Malaysia? We will be flying from LAX. Any help would be appreciated!

Go to Thailand. Within an hour you can make all your hotel reservations and domestice air transport on the internet. I had good luck with Thaihotels.com and Air Asia. Once you get to Thailand any sidetrips you want to make can be made very easily. Thailand is a very tourist friendly country.

Asia's a big place with many wonderful destinations. What kind of things do you like to do on vacation -- beaches and water activities, arts & culture, adventure outdoorsy pursuits, shopping?
Any particular culture that appeals to you?

Without knowing much about you, it's difficult to recommend, but I'd say with two weeks you could easy plan two or three countries. Try to get a balance, like developed/third world, urban/country, different ethnic types or religions.

For example, you could do Hong Kong plus Bali. (By the way, even though Indonesia/Bali requires a visa, it can be easily obtained on arrival at the airport.)
Or Tokyo/Thailand.

See www.cdc.gov for health measures. There will be some boosters of your childhood vaccines they will recommend as well as hepititus A and B and perhaps typhoid. A clinic specializing in travel medicine is a good idea. Enjoy planning your trip!

I agree with Marmot. PLease advise your interests and also budget. Thailand, Indonesia are much cheaper than Hong Kong, Japan so that may play a role in your decision making. IMO in 2 weeks you can go to a maximum of 2 countries, depending on how well you see the country it may even be ok to stay in 1. Countres like Cambodia and Laos are also visa on arrival so actually your canvas is very broad!