As you can see in the photo on the introduction to my dream library page, I have some very ratty copies of some of Mary Stewart’s “gothic” novels. They have recently been rereleased with some very pretty and matching covers. They are British publications and a bit larger than a mass market paperback (5.1″ x 7.6″ as compared to 4.2″ x 6.7″ for a mass market paperback). They are also available as ebooks in the UK (with a few in the US and elsewhere).
My first addition to the dream library then, is Mary Stewart’s gothics, shelved in publication order since they are all standalone stories.