Thanks so much for the feedback and the link to that thread, I had forgotten that! You've been extremely helpful in terms of deciding whether or not to check out Hainach. I was planning on doing a bit of hiking if the whether permitted into the WHS zone but I think it may be too early and I'm certain I'll be back to this area rather often. (As a librarian, book fairs come with the territory and Frankfurt and Leipzig will be yearly via work.) Perhaps I'll visit Hainach before/after the Frankfurt Buchmesse in early autumn, as Solivagant recommends. The Wartburg is a definite hit on this trip. As will a return to Weimar for some preservation work and general enjoyment of the city. I have not been to Erfurt and it looks right up my alley so I am very much looking forward to that and love the recommendations.
I forgot my place for a minute and spoke in Fahrenheit. So embarrassing. :) I have been to the area in the past and have been to most of the WHS other than Dessau-Worlitz, Muskau, and some Luther sites. If I had not been to the area in the past I wouldn't even think of skimping on Dresden and would probably spend all my time there soaking up the beautiful city, museums, and the Elbe Valley. Muskauer Park and Dessau-Worlitz (easier from Leipzig) seem to run into the same problem as Hainach with the flora being integral to the experience. I would probably want to rent a car for either of those, although Worlitz and its components seem accessible almost any way (bus, bike, train, car, even hiking), but again it just might be too early in the year, unless the schlosser at either are that impressive and they don't seem to be.
Anyway, I have been using http://www.montanregion-erzgebirge.de/en/world-heritage-discover/elements/the-saxon-c omponent-parts.html
to check out the Erzgebirge components, so my impressions of this area are purely through photographs and it's a bit difficult to get a sense of all the different components! The pretty pictures of Schneeberg/Schneeberg Mining Landscape may have misled me. I do see the Uranium sites, which look like a fascinating peek into the GDR's past outside of the touristic "DDR" museums. I too am more interested in urban ensembles (hence my interest in the structures, ecclesiastical and secular, that were built with the wealth from ore mining), although a bit of medieval or early modern industry will often be a standout for me (Royal Saltworks, Rammelsberg, Plantin-Moretus
). So I will perhaps check out Freiberg at the very least and continue to look into the rest of these sites. Schwarzenberg (per rec) and the nearby Erlahammer Ironworks are also an option.