I used to take $200 worth of the currency (say, Euros) with me, and have travelers checks for the guide tips--and then use credit cards. Since the trip books now ask that tips be in dollars or local currency, I've given up on travelers checks completely. When we went to Germany I took dollars for tips and that hidden away (all of the hotels have safes), brought about $300 in Euros that I purchased from co-workers and family at the current rate and then, for the first time, used an ATM (in Munich). The fee for the one-time ATM use was not bad, and much cheaper all in all than buying Euros in the US in advance.
People always seem to have some currency when they return from trips, so I would recommend asking around--it is a win win for all, you get euros at the current rate and thus cheaper than from a bank or travel place, co-workers or friends get hard cash for otherwise worthless currency to them (they could cash it is for a lot less, if then wanted to--so they get a better deal selling to you!). I just like the security of having the local currency when I arrive--in case I'm stuck at the airport, or only need bits of cash for coffee or for use in a place that doesn't take credit cards.
BUT ADVICE SOUGHT!! We are doing the Baltic cruise with Disney--many different currencies (mostly not euros, and probably not currency I could get from co-workers). So...buy in advance, use ATMs for small amounts, hope for credit card accpetance...?
thanks all!