This sort of question is floating around my office these days.
We are preparing a 2nd 'release' or 'edition' of a website for our parent company. The new site must 'meet or exceed' the current site's "Capacity". And it's funny to find out what a loaded
word "capacity" can turn out to be.
WebTrends gives us a nice "hits per day" report. But what about the peaks? We can't just divide the hits by 24 and think we're ok. And 'hits' is not the same as 'page views' or even 'page requests'.
We had fancy load
testing software that gave us a "page views per second" (in any given second, how many pages 'finished' rendering) and we were comparing this with WebTrend's "page views" until we realized they were not really the same thing.
Finally it all came down to a Perl script that parsed the weblogs. So we ignored image requests, (because the number of images between the old and new site has changed!) and simply counted pages requested in each minute of the day. Then we convereted this into a nice Excel graph. Pictures are indeed worth a thousand words.