Many airport lounges still sell day passes. This could be a good thing, if you have a long layover. If you know the layover will be long, look at purchasing the pass online before you go. It will save a bunch of money.
Or, buy a Priority Pass. You have access to 700 airport lounges around the world. Great idea if you travel frequently.
Also, check with your credit card company. They may have access to certain lounges.