How much time will you have at the airport? When is the travel happening?

As someone else posted, AAdmiral's Lounges seem to always have signs out front that they are not accepting day passes. If you'll have a significant amount of time (say 5 hours or more), I'd suggest leaving the airport and doing something off-site.

If your travel is after the busy summer season, there's a better chance of being able to use a daypass at a lounge, so long as it isn't one of the long weekends here in the US.