If appropriate, have toys, books, magazines and puzzles in your waiting room.
Both parents and children appreciate having the distraction. If your office is a little more highbrow, simply keep the toys in a nice chest and offer them only when children are present, rather than leaving the toys out at all times. Waiting rooms are not ideal places for high-energy children, so even having these things available for staff to hand out can go a long way toward making everyone’s visit a more comfortable experience.