Exclusively DT except for #51 Black House which I got with the #51 DT group most of my books are from, and a #36 Eyes of the Dragon. I wanted to incorporate into my home office/desk/gaming area and had wanted to put together a DT collection. Have other books in other rooms for reading, but keeping collection small for now.
Since originally posting collection, I've also been lucky enough to add some amazing art that helped take my enjoyment and Dark Tower focus to the next level. I have added works by Michael Whelan's and Rachel Readman's as well as their collaboration, The Crimson King sculpture. https://rachelreadman.com/ and http://www.michaelwhelan.com/
#51 of DT I, II, III, IV-S, V, VII, SoE & #51 AE SoE. #96 III, #226 IV, PC VI, #293 VI, Gunslinger 1st-1stp & 1st-2ndp (unsigned). Since i don't have very much display space, random reading books are on shelves in closets. I have unsigned 1st editions in a hallway area right next to office my wife just allowed me back in after remodel :-)