Why this is a luxury trip, not a budget one
Worth saying plainly because the assumption runs the other way.
These are small ships with high crew ratios, all-American builds and crews, included shore excursions, and fares that sit alongside the European river lines rather than below them. What you are buying is the same thing you buy on the Danube: space, service, and somebody else handling the logistics.
The difference is what it costs you to get there. No transatlantic flight, no passport, no jet lag on either end, and no day lost at each end of the holiday. For a lot of people that is the entire argument.
When to go, by river
The Mississippi runs most of the year. Spring and fall are the comfortable windows. Summer in the Deep South is exactly as hot as you would expect, and the ships are cold inside, but the shore time is warm work.
The Columbia and Snake is best late spring through early fall. The gorge is green in spring and golden in September.
New England and the Hudson is a fall trip above all. Peak color sailings book a year ahead and the good cabins go first, because there are only so many ships and only so many weeks.
What catches people out
The ships are genuinely small. If you are expecting a resort at sea with four restaurants and a theatre, this is not that. That is the appeal for most people who try it and a disappointment for the handful who wanted the big-ship experience.
Single occupancy is unusually workable here. Several of these lines have real solo cabins rather than a punitive supplement, which makes this one of the better categories for anyone travelling alone.
It suits mobility limits better than most cruising. Elevators on most ships, short walks ashore, no tender boats. Worth knowing if that has ruled out other trips.
Book the fall sailings absurdly early. New England in October is the single most requested window in American river cruising and the arithmetic of supply is not in your favor.
I book these nationwide
River cruising is a specialism, not a location. I plan these for clients across the United States, and where you live makes no difference to the trip or to what it costs you.
The fare is identical whether you book direct or through me. What changes is having somebody who knows which rivers suit which travelers, which cabin decks are worth the jump, and which sailings fill before they are advertised.