Yes, the Seine boat tours are worth it. Sometimes.
At night, not during the day. A little rain is good, a lot of rain is a no no.
I used to recommend the ones by the Pont Neuf, but it doesn’t really matter. They will all tell you the same over repeated ad nauseam facts that you have heard by now, and if not their lack of enthusiasm will put you off anyway.
Look around, take your pics, kiss someone while going under the Pont Marie bridge and enjoy the fantastic scene that is Paris from the Seine.
The most famous ones are Les vedettes du Pont Neuf (Métro Pont Neuf), Bateaux Mouches (Métro Pont de l'Alma) and Bateaux Parisiens (Near the Eiffel Tower). Pick the one that fits your itinerary better.