With kids, sometimes offering choices will diffuse a situation. Would you like to do ___ or ___ seems to work better than just DO THIS. I definitely would agree with lots of engaging toys like Play Doh and simple games. I remember a particularly long trip when my son was three and he was obsessed with the Disney version of Robin Hood on tape. By the time we got there, the expression for excitement for everyone was "Oooh da LAH lee!"