We recently did a bit of furniture rearrangement, part of which consisted of reuniting two bookcases and creating a 'book nook' in the corner of the living room. It doesn't feel quite like a reading nook, since the closest chair faces away from the bookshelves, but I did add an Ikea stepstool and a sheepskin rug on the floor, so there's at least a comfy place to linger.
I made a deal with myself some time ago that I'd start only buying books I love (or really like). I don't own every book that falls into that category, but they're slowly being added to these shelves, filling up the gaps and replacing ones I don't feel as strongly about.
Also making an appearance: beloved books from childhood. I find it very sweet to revisit them. My latest purchase was a gorgeous compilation of Beatrix Potter's tales. Tom Kitten always makes me smile.