My cousin and I are trying to plan a trip to the cities listed above. I live in Seattle, WA and she lives in Souix Falls, SD. What is the best mode of travel? Bus, rent a car, train, other? Any must sees or avoids that we should know about? We want to see all the usual stuff and historical sites as well. We have been looking at a bus tou,so neither of us would miss out on the sights if we had to drive and pay attention to the roads. Haven't seen very good reviews for the bus tours. Planning on at least 10 days in mid to end of September. Is it best to fly into Boston or New York and if so which airport? Any help would be much appreciated.