Slight modification re: changing currencies. Don't bother with travelers checks and don't go to a bank (or, worse, a "Change Bureau"). Do what you do here: put your ATM card in the machine, punch in your PIN and how much local currency you want, and the machine spits it out! Far more convenient, and you'll get a much better rate than any of the alternatives. At most a ~$3 fee (as opposed to substantial "commissions"); some US banks don't charge a cent for foreign withdrawals (I opened an internet account for just that reason; it saves me maybe $50/year).

Best of all is that this can also solve the problem of converting from eastern European currencies back into dollars: if your bank doesn't charge for the withdrawal, just remove minimal amounts as you get to the end of the trip. Who cares if you might need an additional withdrawal (or two) - no cost!

Alternatively, I use the leftover currency to pay down my hotel bill, keeping just enough to get to the train station or airport. Then the remainder goes on my credit card. This also avoids having to change currency back.