It is great fun to see the bookcases (and collections). My house is decorated in bookcases and maps, for the most part. In our humid climate, bookcases are against inside walls only.
Here are topically organized shelves, Chess set (tournament size) on the top, then some theory books, mountaineering guides and reports, bicycling, geology and ecology.
Full length shot of the pine board bookcases built by DearHusband, decades ago now. This one is filled with favorites (Nevil Shute and Robert Heinlein on top shelf, and Make Way for Ducklings and Paddingtom Bear on the bottom)
Shakespeare, Owen Wister, TH White, Madeline L'Engle (new addition - that's a graphic version).