I've read a fair number of these papers (50?). Most are excellent, a few represent ideas that still need work, and a couple seemed silly. If you want a serious read on almost any topic (future Titan exploration, for example) just search through these for an excellent background on the science and possible missions.
There's one downside, though. The papers are listed at the Decadal Survey website across 10 web pages in the order in which they are submitted, making a search time consuming. (Google searches weren't working well as of today. Mostly, you get hits on entries from this blog.)
So, two alternatives. I will continue to summarize and comment on the papers I find most interesting. Alternately, you can go to the websites of the various analysis groups to see the white papers for their subject areas. Here are links to the analysis groups (listed in the random order I first found and bookmarked the pages):
All papers (see links at bottom of page to other pages with papers)
Small bodies (SBAG) - asteroids, comets, trans-Neptunian objects, small moons
Outer Planets (OPAG)
There are a number of white papers that didn't fit into these categories (e.g., Deep Space Network upgrades that could increase data return from missions several fold). For them, I've compiled the ten web pages hosting all the input into a single Excel spreadsheet. The papers are still listed in the order published, but you can search on a single page. E-mail me at vkane56[at]hotmail.com if you are interested.
Oh, and it may not be exactly 247 papers. Some papers were posted multiple times as they were revised, and I don't know if the drafts are still on the web pages. (I have a life so I didn't check.) The true number is still over 200, which represents a treasure chest for anyone interested in future planetary exploration.
Example of white paper listing on the Decadal Survey web pages.