evening/night canal cruise small boat

Location ?

Have heard red light dist. at night is fun.
General cruise to see a little of the area.
Do the hop on hop off work well?

No idea why people want to see the Red Light district . It's a small area and most of the 'girls' are foreigners who were lured to the Netherlands by false promises of great jobs . A pimp will 'need' to see their passport and then keeps it so they can't even go back home . There's a lot of misery in that area .
Small Boat : Many tour boat companies available including H-O-H-O, day time and night time.

Small boats may not have a roof so check that in advance if the weather looks iffy for rain.

Check out AirBnB Experiences - you can book an evening boat cruise around Amsterdam which includes drinks (beer, wine, etc) and traditional Dutch foods. It is more expensive than a "cattle car" cruise but you get more of a 1 on 1 experience.