Shelving / Storage solutions in small-ish space? [View all]

hey -- after all these years, I think this may be my first post in this group!

In any case, I've downsized from a "house house" to a "guest house" -- less room in a leafier neighborhood, but my nest was emptying anyway...

Still, despite giving away lots of books, and stuff, there is still.. well, books & stuff. Mementos from my boys (when they were boys), recently departed dad, etc.

In any case, I need to figure out more shelving solutions. I moved last fall, and still have boxes that remain undealt with because there is nowhere for the "stuff" to go...

I have reasonable latitude here about affixing stuff to walls, if need be...

What are some of the favorite shelf solutions for the group?