With the text file traffic data I get, I parse text into columns using the space as a separator. I find this puts the information into very useful columns.
I then sort all the rows of data by various columns to give me some very interesting information. For example I can sort by the file downloaded listing as secondary sort values, the date and the time. Looking at all the visitors who downloaded the robots.txt file for example, I get a good feel for which robots visited and how often.
I only do this when I really want to get the nitty-gritty. I find Funnel Web Analyzer (freeware) is what I use routinely and this gives me most of what I want.