As of this writing, Pantheon site aliases are only compatible with Drush 5.
If you're using a newer version of Drush (6, 7, 8+), you'll likely get the following message when trying to execute a Drush command with a Pantheon alias:
$ drush @pantheon.xxx.xxx status
Unknown option: --db-url. See `drush help pm-enable` for available [error]
options. To suppress this error, add the option --strict=0.
There are two possible workarounds:
Provide the option
--strict=0 to each Drush command
$ drush @pantheon.xxx.xxx status --strict=0
Install Drush 5 and use it specifically with Pantheon
If you're a Mac user and use Homebrew, the second option is as simple as:
$ brew install drush5
$ ln -s /usr/local/Cellar/drush5/5.9/libexec/drush /usr/local/bin/drush5
$ drush5 @pantheon.xxx.xxx user-login
The first method works for me using Drush 8.1.9 and Drupal 7.53 (and optionally Terminus 1.0.0) on macOS 10.12.3 "Sierra". I have not personally tested the second method.
In either case, be sure your Pantheon aliases are up-to-date:
$ terminus aliases
[notice] Aliases file written to ~/.drush/pantheon.aliases.drushrc.php