My father, now 70, has been a meticulous note taker and archivist most of his adult life. He has never really been a news junky or the like, but most of his notes would be interesting, I think, to people studying Manufacturing in the US during the last third of the century (late 60's - early 2000's).
So the question I have is how do I find the best place for these papers? I mean, I know the answer is most likely not very useful but I don't want to waste an opportunity for someone to have access to an industry that has changed tremendously over the last 40 - 50 years.
They'd make sense, likely, in many archives, particularly if you're near a public university with a decent library. If the documents you have are mostly local or state based, then keeping it local would help people who are researching the history of that area (example, if the documents detail manufacturing in Houston, then either Rice University or the University of Houston would be a good place donate them.) If you want to vet various archives, I'd suggested checking out a few things so you can decide how accessible your collection would be. First, does the archive have a useful online search function. Second, does it seem to have a specialty in a particularly subject (see what they list as their big archives under "special collections"). Third, is it something with permanency where people actually go? Local history societies are great, but they often lack funding, and if they fold, their collections can get scattered. They also sometimes don't have the highest visibility to researchers with limited time and budgets who'd prefer to make 1 stop at a central archive than 5 at small county societies. If the first place you go isn't interested, try another.