I did a search on CC in this forum and went back 4 pages but didn't really find my answer. I checked with my CC company and they stated that I can use the card w/o any exchange fee's/charges if the merchant charges in USD. If charged in local currencies there is a 3% charge/transaction. So they advised me to ask the merchant to charge my card in USD if I have a choice.
What is the norm?
Do they charge in local currency?
Do you ask them to charge in USD?
Or is it better to have them charge in local currency and pay the 3% fee and pay the $3.00 on $100 dollars spent?
I was looking at using the card primarily for the larger expenses that I accrue.

The Dutch side will charge in Dollars but French side will charge in Euro. If you ask the merchant on French side to charge in Dollars instead of Euro they will convert it with whatever exchange they want to which could be more than the 3% the CC will charge. All my CC's, Citi and Bank of America, don't have any foreign or conversion fees. You might want to look into getting one of those.

If you're on the Dutch side, they have always charged me exclusively in Dollars, so it shouldn't be an issue. On the French side, you may have to engage in some mental gymnastics if you're so inclined, and compare their exchange rate differential to the 3% vigorish to determine the better way to charge. But, some places only charge in Euros. Also, some places offer a better exchange rate for cash $, so you might want to use cash in places that offer favorable exchange rates for cash.

And, I am aware that many folks don't want to engage in these mental exercises during vacation.

That's interesting. Citi bank is who I talk to. The conversation I had with them was what I explained in my question above.

The key is to have a card that doesn't charge either foreign transaction fees or currency conversion fees; they are two different things. Once you have that card, you should have your French side charges put through in Euros, which will get you the best available conversion fee when the charge hits your account. Dutch side charges are always in US dollars.

Citi has numerous cards; some charge fees and some don't.

You need a platinum Citi card to get that which is easy to get.

I have three CC's and neither of them charge foreign exchange fees...easy to find and becoming more common

There are sn incredible number of credit cards out there, all offering different features. We are very partial to our JB cards for airline points and our Capital One for cash back and the added bennies of no foreign conversion fees and both cards charge no annual fees. There’s something out there for every need.

Never an issue charging on the Dutch side in US dollars and no need to ask but we do usually request we be charged in Euros on the French side for the accurate daily conversion rate with our card.

Try getting a Capital One VISA card. I closed my card with Citi Bank for the same reasons you experienced above. It's also important to have a zero percent foreign transaction fee if you ever plan to visit Europe. Many countries won't charge your card in U.S. Dollars so having a card with flexibility is a good idea.