Do the boats run at night? Also does anyone know if a boat runs from the Spui area to the vicinity of the red light district?
There are a bunch of evening candlelight dinner cruises. This company operates the cruises from the Rokin dock which is close to the RLD: http://www.rederijkooij.nl/index_en.html They have another dock at Liedsplien which is closer to the Spui neighborhood.
I don't know about the boats. But it's only about a 10 minute walk between the red light district and the Spui, or 2 tram stops. So even if your boat is round trip, you can easily get from one to the other.