Bitcoin as a meta currency seems very useful if travelling through multiple places using currencies. I had this very intention for when I travel around asia.
What is the best method people have discovered for having the most flexible use of bitcoin when switching back to native currencies in such a manner?
Obviously, keeping fees as low as possible would be excellent.
You should be wary when trying to travel only on Bitcoins, some people have failed in the past.
At the current stage of development, Bitcoin is not ready to be used to finance your local spending across multiple countries, as getting money to and from an exchange takes a long while. Moreover, you can't withdraw money easily this way into a foreign currency, so the model would work like holding all your money in your local bank and using a debit card to withdraw money at an ATM.
You could potentially have your fellow Bitcoin enthusiasts offer to sell you local cash for Bitcoins on the spot, but that would require a lot of preparation, contacting people, and trusting them to show up on time when you need the cash. Generally, not an ideal situation.
All in all, it can't really be done at the moment. Maybe in a couple years...
Update: BitInstant has announced that they will be releasing an international MasterCard funded by Bitcoins in a couple months.
Bitcoin is different from a Western Union, for instance. Western Union has 500,000 agents located around the world but each is operating with explicit approval from Western Union.
Bitcoin has no such restriction. Exchange can technically be performed by any individual working independently. All that is needed is a supply of cash and a mobile smartphone to run a bitcoin wallet app and to see the current exchange rate.
This activity doesn't occur much yet, but when it does it will likely be found first where travelers and techies are found -- coffee shops, hotels, hostels, hackerspaces, etc. If any of these accept bitcoin themselves, they might already use the service of a local exchanger to convert their bitcoins back into cash. These places would know how an in-person exchange could be found or they may offer this service themselves as a courtesy to their customer (just as a hotel might cash a check for a guest.)
There are directories of local traders, maybe there are enough exchangers already where this approach would be used for at least some of the trip.
