We visited Saut du Doubs (not Doubts!!) when there was snow on the ground, so the boat trip down river was beautiful with terrific views of the Swiss side and snow capped houses in the valleys. The boat guide was very informative (though all in French) and the boat trip alone was worth the fair. The short walk (20 mins) at the end of the boat trip to the falls was lovely, and this ends in a stunning cliff-top view over the river and the falls. I would also recommend the pizzas in the Chez Jo next to the boat ticket office, simple, unassuming cafe-style place but great pizzas.