Mrs R and I have ridden Amtrak Seattle to Chicago a couple times, which is a good solid two days. We changed clothes once, at the beginning of Day 2. We had big suitcases we left in the downstairs luggage area, and small hand bags to carry a change of shirt and underwear, amusement supplies, toothbrush, etc. Periodically we visited the larger luggage to retrieve something or other.
(I do want to say that my favorite luggage movie is Joe vs the Volcano.)