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.