The first thing I do with site inventories to do a quick scope assessment survey of the site - just note down the basic hierarchy and count of pages, don't worry about the finer details. This sometimes reveals surprising assumptions - one Wine Sellers website turned out to have less than one hundred products, something which got missed in the briefing. All their competitors had many hundreds going on thousands of products.
Another tip when doing site inventories is to request server access logs, and use those to determine priorities for attention.
These can also turn up long lost sections of content, where there once were links in the site but which have since been removed, and where despite no links in the site you might still be getting lots of traffic courtesy of google or other third party links.
I also use a home-brew Filemaker database for logging my site inventories instead of Excel. Not only can I view the web pages directly alongside the data records, this lets me script extra functionality such as one-click scripts to import a page's title, summary, meta-tags; storing of screen caps of interesting pages; and relational data structures for tracking page templates/types/modules/patterns.