When different users of different time zones (EU, US) and servers in other time zones (Asia) works together it is confusing talking about peaks happening at a certain time.
So it would be greate if we can set per user or per host the time zone where it is located.
Then the graph time axis could be noted in the "right" timezone. This helps to find what happens at 02:00 (your or mine time?) and synchronize with syslog etc.