I believe it depends on both the credit card you have, and the country it was issued in.
Taking one example, if you have an American Express Platinum card then you get access to quite a few worldwide lounges at any time, and several airline lounges when flying with that airline in any class. The current list of lounges for US customers is here. The country thing does affect you - while both US and UK card holders (as an example) get Priority Pass lounge membership, I'm told that it's at different levels. As a UK card holder, you get a priority pass card that works anywhere in the world. If you're a US card holder, then your priority pass is a "select" level one, and isn't valid at most lounges inside the states.
So, depending on what card you have, and what country issued it, and what deals are currently on offer, you may or may not get free access to one or more lounges in any one airport. What you'll need to do is check with your card issuer before you go. (They'll hopefully have a website with the details). Also, one thing to be aware of is that if you get some sort of free Priority Pass membership, you almost always have to carry the Priority Pass membership card with you. That means you need to have filled out the form your credit card company gave you, sent it back, waited for the card to turn up, and then carry that with you in addition to your credit card. At most PP lounges, no PP card means no access, no matter if you have the card that offers the free PP membership with you.
Finally, if you won't have free access to a lounge in the airport, you can often buy a pass. Priority Pass for example will normally sell you one for their lounges, and there are lots of websites that'll sell lounge access, typically for 3-5 hour visits. You can't buy access in all airports (Heathrow Terminal 5 is one that has no pay for lounges - it's One World status or Business+ tickets only), but in most airports you can buy access to at least one lounge (normally not the best one...) for not insane amounts of money.