if you have cs5, you can open in cs6 (and cc).
you can always deactivate cc 'after the fact'. ie, if you attempt to install cc on a 3rd computer (2 are allowed) you will be prompted to sign out of your other 2 computers to all you to install.
if you have a cs5 serial number when you travel, you can install cs5 on a borrowed computer but that gets a little trickier in that you'll want to remember to deactivate before leaving that borrowed computer.