Vote for Terminal services log
Terminal services log will provide exact information on your users' activity on terminal servers, showing how long each user was connected to the server, how much of that time was idle (not working on anything) and how long the user was active (working on something on the server). It will provide valuable data and you will have direct evidence on to how long each user was active over the day.
Terminal Services Log first logs sessions for every user connected to Microsoft Windows Terminal Services or Citrix Presentation Server. Data that is captured: Connection start (date and hour); User; Duration; IDLE time; Active time; Disconnected session time; Connection end (date and hour); Status; Analyze data.