If you are going to take it in cash then I would split it up between your party, even if you just give it in envelopes to the two teenagers to carry (if you feel that they are responsible enough). I would just not like to have all your eggs in one basket. I think if you tried to swap to traveler's cheques or to put it onto a credit card you will now loose out on the exchange rate or through transaction fees. In saying that for what you may be charged it might be worth it for the security/peace of mind. Did you get all of the cash from one source, as they may be able to assist you with any such request.