One of the interesting things about traveling around multiple countries that I've never dealt with before is currency. In SE Asia, with distinct cultures and histories, everyone's got their own currency (with its very distinct conversion to USD!). Fortunately(ish), we are able to use USD here and there throughout our whole trip. However, it's always good to try to support the strength of local currency as well as preparing yourself for smaller vendors not wanting to see good ol' Lincoln in their pockets. Here's what we'll have handled by the end of our trip:
South Korean Won: Used on the Korean peninsula exclusively.
Approximate conversion to 1USD: 1,000-1,200KRW
USD accepted in South Korea? No.
Thai Baht: Used in Thailand and in neighboring regions of Myanmar (Burma), Laos and Cambodia.
Approximate conversion to 1USD: 30-33THB
USD accepted in Thailand? No.
Cambodian Khmer: Used in Cambodia. Also called 'Cambodian Riels'.
Approximate conversion to 1USD: 4,000- 4,100KHR
USD accepted in Cambodia? Yes.
From Lonely Planet, I've heard it's good to have about $10USD worth of riels around when traveling through Cambodia, though ATMS will dispose USD when withdrawing cash.
Vietnamese Dong: Used in Vietnam.
Approximate conversion to 1USD: 20,000d
USD accepted in Vietnam? Yes.
In Vietnam, however, ATMs will dispose dong as oppose to USD.
United States Dollar: Used in so many countries it makes my head spin. For this trip, we will use USD in Cambodia, Vietnam, and Malaysia (during a layover).
Basically, it never hurts to have some USD around, but make sure to have local currency on you too. AND, as always, wear a money belt or keep your money hidden tight!
I'm just about done with half of my currencies, narrowing it down to the final 3 before heading home. Hopefully the conversions will come easy; if not, I'll be adding a calculator to my packing list for future ventures.