Unlike the Arlington stores, the two Dallas stores that I visited after work (the Big Main Store on Northwest Highway near I-75 and the one on the southbound service road of I-75 between Belt Line and Spring Valley) do not have their miniature books gathered in one spot, near the gift items. When I went to the second store, the clerk told me that since they didn't sell very well, they were tucked among the full-sized books of their type, and the most likely places to look would be Religion, New Age, and Self Help.
Since I already have a book of Georgia O'Keeffe's flower paintings, I hit the Art section first and found a gem. Moving on, I found a pocket edition of Khalil Gibran's The Prophet. Ta-daa!