You have got to check out the great selection of puzzle and game books at Puzzle Plus. No matter what your favorite paper and pencil type game—crossword, Sudoku, cryptograms, logic games, whatever—P+ has got it. I am a huge Sudoku fan and brought along Frank Longo’s Dial S for Sudoku on a recent business trip. With 246 puzzles ranging from easy to VERY challenging; puzzles large enough to see and easily write in; and a book that folds flat for easy handling in an airplane or car (not while driving!) this book greatly enhanced my trip and kept me entertained.
The Brain Games series of books is also excellent! I love their Logic Puzzles book especially. The Brain Games books are specifically designed to lower your brain age. Certainly we could all use a little of that!