In all the goodness PRTG delivers there is one thing that is bugging me quite often. Sometimes a situation that is very well illustrated in graph form does not at all fit in one of the pre-defined timespans (I use 2h, 2d, 30d, 365d). Say it lasted 4 hours. I will be a short blip on 2d graph and start 2h before the 2h grapth.
I usually manage to get the information I need from the graph, but very often one view does not capture the incident from start to resolution. And since the PRTG graphs are pretty and is a very nice way of communicating and documenting, I sometimes even send a screenshot of a graphs to a customer.