Whenever my family visits me from overseas, I'm usually too busy to be with them all the time. When that happens I hand them "Tabi no Yubisashi Kaiwacho Japan" and let them loose. This is the book I recommend for anyone who needs a quick and easy method of communication while in Japan.
It is also very useful as an amusing picture dictionary for beginning (JLPT 4 & 3) Japanese language learners. I still use it to review some vocabulary and kanji for Level 2 when I lack the energy for heavier reading.