I took this on with a past employer. After much discussion, we opted AGAINST .pdf as the sole electronic distribution method due to the extra load time, annoying software, and (somewhat) questionable visibility with the search engines...I know, I know, Google does search .pdfs....but it seems to grab traditional HTML sites BETTER.
So, our solution was to deliver the site in newspaper format via a custom CMS that we wrote in-house. We could then use Google Analytics to track inbound, outbound AND search related traffic plus paths through the site. A big part of the traffic we received was referrals from current readers, and there was no way to track who's passing around a .pdf via email forward. It's easy, however, to track a "send to a friend" link on a site...which is why you see it on CNN, MSNBC, etc.
An added bonus is that by doing it the way we did, we could use queries (or RSS, which we also offered) to cross-post the content back on the main site and the 25 other sites that the company ran. So, a particular letter from a high-ranking CEO could be used to populate multiple newsletters and websites with just a few clicks.
Later, to appease the print-obsessed crowd, we did begin offering a .pdf download, generated on the fly server-side. Sure, it wasn't a perfect, custom laid out graphic marvel...but it worked, was automatic, and people liked it. Load time for the .pdf was ~20-30 seconds if your .pdf viewer wasn't open. Load time on the non-pdf site was about 1sec by comparison.
Administration-wise, we went from hours per newsletter down to less than an hour. An accompanying email system was setup to auto-generate a email blast with the month's articles, with just a handful of clicks. The email blast immediately ratcheted up viewership and doubled return visitors.