For roughly the same price as a 1 hour canal cruise, you can buy a day ticket or 24 hour pass for the 'canal bus' which operates on three different routes stopping at 18 different popular locations. There is a multi-lingual commentary through-out and the captains are very friendly and helpful. We spent pretty much a entire day using their service and its great for either going to specific attractions you want to visit or to just relax and enjoy the sights from the canals.
We personally went for a 1 day pass at 20 Euros each rather than a 24 hour pass for 22 Euros as they only operate between 10am and about 6pm although you should check their website as times and prices may change according to the season (we went in March).
As a side note, our hotel suggested we avoid a dinner cruise on any of the other canal boats. Apparently the food is like 'airline food' and they are very, very expensive. Go for the canal boat - you won't regret it especially if you intend to visit a number of attractions along the way.