May want to call out performance differences between OrderBy().OrderBy().OrderBy() vs OrderBy().ThenBy().ThenBy().  Jon Skeet talks about the differences in a popular SO question: http://stackoverflow.com/questions/3760001/linq-orderby-versus-thenby.  He also reimplements these all of the linq functions in https://msmvps.com/blogs/jon_skeet/archive/2011/02/23/reimplementing-linq-to-objects-part-45-conclusion-and-list-of-posts.aspx.  I'm not sure how relevant the second link is, but I read the posts about reimplementing OrderBy() and ThenBy().  From those reads, the posts seemed like they'd all be pretty intersting