My family decided to plan a trip from NY (Oneonta) to Yellowstone National Park. We will have 22 adults and 7 kids. We are looking for the most cost effective but enjoyable way to travel. We are planning two weeks so we can make some stops along the way. I'm looking for advice on modes of travel (train, RV, etc) and different sites to see along the way. We are planning this vacation for the summer of 2015.