There is a website called pennycollector.com that has locations of machines all over the country, and more importantly, it has tips on how to get the best impressions, and what kind of pennies to use etc. My Dh and his sisters are bigtime squishers, so they're officianados of that website!
If you look at up the Florida locations at WDW, it says "too many to mention!" so bring lots of pennies!