A few more links you may find interesting as you read through these:

Sayers litcrit postings (http://truepenny.livejournal.com/tag/dls) by author Sarah Monette (aka truepenny) -- she revisited all the books in order, you'll need to skip back a few pages to get back to the beginning. Lots of interesting discussion in the posts and comments.

The Wimsey Annotations (http://www.planetpeschel.com/index?/wimsey/index/) -- this would be the DLS equivalent of Jess Nevin's comic spot-the-reference guides.