“What Pet Should I Get?” by Dr. Seuss; Random House Books for Young Readers (48 pages, $17.99)———There are moments of uproarious fun in Dr. Seuss’ never-before-published picture book, “What Pet Should I Get?”Theodor Seuss Geisel, better known for his more fantastical creatures — the Grinch, Things One and Two — proves himself just as capable of conjuring the ordinary house cat’s supreme self-satisfaction and the archetypal good dog’s sincere desire to be of service.