There are no sea days on a river. You go to bed with a castle on the hill and wake with vineyards running down to the water, and the ship has done the moving while you slept.
It is the part regular river cruisers describe first: unpacking once, then watching a country arrive through the window over breakfast. No airports, no transfers, no repacking a case every second morning.
By the end of the week you will have crossed several countries and never once queued to do it.