Charge in US Dollars or Euro?

While I have not worked out the math on the one or two transactions that it occurred to me, I see no reason to have the charge made in something other than the local currency. CC exchange rates tend to be very good, and you still would not avoid any international transaction fees, or perhaps even an exchange fee. To have them make a conversion from Euros to Dollars only opens up the possibility for them to charge an unfavorable exchange rate. Perhaps the only instance it might make sense is if they advertise or you negotiated a hotel rate in US Dollars, in which to insist on local currency would force a conversion.

when they offer you to charge in USD, they are often adding a huge conversion fee (3-5%, sometimes even more from what i've read). You are better to just charge in local currency and also use a capital one card to avoid the extra fees.

You'll always get a better rate if you have charges posted to your account in euros--I have a Capital One card mentioned in another response to your question and have found it very satisfactory. You will still be charged the Visa/Mastercard fee for the exchange, but Capital One does not add an additinoal fee, as many credit card companies do.

You'll always get a better rate if you have charges posted to your account in euros--I have a Capital One card mentioned in another response to your question and have found it very satisfactory. You will still be charged the Visa/Mastercard fee for the exchange, but Capital One does not add an additional fee, as many credit card companies do.

Local currency is usually best. It avoids the potential "hidden" surcharge the proprietor can charge for conversion. To date, I've not had a problem having my credit card charged in local currency.

It can vary an awful lot depending on which country you are in. My experience is that there is no real difference between being charged in local currency or USD in some countries and in others ( Greece, Czech Republic and the Scandinavian countries in particular ) you are well advised to pay in local and let your card company do the conversion. Always ask what the conversion rate is and if it’s either to high or the cashier does not know – pay local.

Keep in mind that even though €1 has got the purchasing power of $1 you now have to pay $1.40 to get €1. That's like there was a 40% tax on everything you see, you pay. For that reason try to keep your currency conversion fees to a minium and always pay in local currency. That way you only need to pay the conversion fee once!