We're on the Navigator Amazon cruise in 10 days. It's been waitlisted for ever. A couple of weeks ago, the was a sniglet of opening for guarantees in the stern cabins and one lonely E in the very front of the ship.That disappeared almost instantly. Now it's waitlisted again, across the whole ship.
As much as the little Navigator gets bashed regularly (unless you're a devotee, as we are), it still has the best itineraries of any Regent ship, imho.