Plus - as long as you travel on AC metal in C /there are some small aircraft with Y-class only/ - you should also get UA Club access in PHL.
Star alliance lounge finder:
http://www.staralliance.com/en/web/s.../lounge-finder
PS. In YYZ you can only access International lounge - it is because of how the airport is set up.
PS. US-to-Int transfer in Canada requires you to clear Canadian immigration - make sure you do not need a visa for Canada (I believe you need one if you are a citizen of Panama, if you are a US citizen you will be fine) - otherwise they will not let you in.