If we use our American cell phone in Europe to call a European destination is it as if we're calling from America (ie: need to use the international access code) or is it as if we are calling from Europe (just area code first)
Patty,
As the previous post mentioned, you'll need to first ensure that your U.S. phone will even work in Europe. If you are on a contract plan with either AT&T or T-Mobile, you'll be able to "roam". I believe AT&T has an "international roaming plan" which provides slightly less expensive rates (you'd have to check with them for the details).
If you are with one of the above networks, you'll also have to determine if your phone is a quad-band model. If you're planning to roam with your home network, you won't need to worry about "unlocking" the phone. If that's the case, I'd strongly suggest telling friends and relatives NOT to call you while you're travelling, as the costs will add up quickly (they'll be dialing your local number, you'll be paying the charges to Europe). I find text a much cheaper option to keep in touch with friends and family.
Have a look at This chart for some information on your original question.
Happy travels!