And for a time I was able to force myself not to find the ideal place for all those books, just get them out of boxes and onto shelves.
But then I had to go get myself distracted by Wikipedia: Library Cataloging and classification. Where I got to read about the differences between the Dewey decimal system and the library of congress system.
And then I learned about the Universal Decimal System and that they have a summary of about 2,000 classifications in Browseable form
Now I need to resist the temptation to install some library cataloging software and go stick call numbers to all my books.