PTY is an easy airport, you're in the concourse and go wherever. It's brilliant for making connections. I've heard it's a nightmare for customs/security but since I've only ever transited I can't speak to that.
There's a really overpriced, crowded, small food court...it's like $12 USD to get a Quizno's combo. Gougers!
Also there may be areas where the AC doesn't work, stay the hell outta those hot spots lol.
That said, it's 11 hours, presumably you have no lounge access, not that the Copa Club is amazing. The airport is small (trying to be big) the bathrooms are pretty terrible, limited food, wifi is...average or below average, terminal has lots of seating but it can get kinda crowded too.
There's 2 good things about this airport.
- Electronics stores, there's multiple stores selling cameras/dvd players/ipods/gaming systems and everything in between. If you're a tech shopper you can kill 1-2 hours doing that and maybe find a sweet deal.
- It's great for connecting passengers.
But 11 hours? You'll wanna kill yourself. I really suggest looking into going into the Canal or even just venturing into town for a stroll/lunch or something. Even if customs is a HUGE mess you've got lots of time so you shouldn't be rushed.