Hi,
Under the circumstances it seems like you are doing the best you can. I am not sure if the fact you can't use actual user credentials is an issue. If the goal is to test the Citrix server performance then it is actually better if more unique users will login and each perform his real day to day workflow rather than all doing the same flow.
Regarding monitoring, I suggest also looking at transaction response time, application log files and key performance metrics of the application/OS.
Needless to say that by doing the same test with Vusers the test will be more systematic and allow you to run several cycles until you are satisfied with the results.
Good luck.
Shlomi