But you shouldn't miss the chance of using the real log file of the web server, because it also tells a lot that the external tools mentioned above doesn't tell.
The web servers own log file will tell you all about errors and hits to files. So if you have a lot of traffic to a specific PDF-file or an old webpage which doesn't exist any longer, this log file will give you this valuable knowledge.
At Semaphor we are using our own tool Web Log Consolidator to consolidate all log information from different servers, which is relevant for a specific customer. After assembling a log file for the customer, we run this file through AWFFull (a Webalizer fork) to generate a report for the customer. There are lots of other backend webserver log analysis tools you can use. 10 years ago the most well known and widely used commercial tool was WebTrends.
We'll be happy to help you getting a grip of this valuable data.