I have almost as many quilt history books as I do quilt patterns/techniques books so they are kept on separate bookshelves in different rooms. The techniques and patterns are in my sewing room shelves, categorized by piecing, applique, color studies or general. My basic all in one how to do quilting stuff book is the easiest to get to since it is the one I refer to most often.
My quilt history books, plus several oversized books that won't fit sitting up on a regular bookshelf, are in the bookcase in the den. This is where I sit while browsing through the antique quilt photos and stories at my leisure dreaming of replicating some of those designs.
By the way, I keep an inventory of my quilting books on
http://www.librarything.com. It's a free service and easy to use. Also, it helps prevent me from buying a duplicate book if I check my list before making a purchase.