I've stayed on the Herengracht and found the area to be quite peaceful, but if you normally live in a rural or very quiet suburban area, your perception of peaceful might be very different from others who live in a city. If you are a really light sleeper, seek out a higher floor or forego the canal view and ask for something that doesn't face the water/street side as you will hear some of the boats cruising past on the canals, a few cars, and bicycle bells ringing. Very few hotels actually have rooms that are at street level as the lobby/reception area typically occupies that space.
Don't limit yourself to only those hotels/B&Bs listed in Rick's guide. They tend to fill up very fast with other blue book devotees and then people panic when they can't find a room. Do a search for other options in your established price range in the area you want to be, look over photos and read reviews carefully to see what other travelers have to say about the hotel and the location. Use Google Street View to scope out what is located immediately near your hotel - you don't want to end up next door to a nightclub.
If you have any sort of mobility issues, or just tend to overpack and bring very heavy luggage wherever you go, then I would recommend you look for something with an elevator. Many of the hotels occupying the old canal homes have rather steep staircases. The canal buildings also sometimes have strange layouts because of their age. At the hotel I stayed at on the Herengracht, I had a room on the 5th Floor and when you would get off the elevator, you had to walk down a hall, go down 2 small steps, down another hall and walk up 2 steps and inside my actual hotel room there were 2 steps that you had to walk up to get from the bathroom/dressing area to the bed. Not a problem for me, but for someone using a wheelchair, walker or cane, it would have been an issue. If you think this would present a challenge for you, ask the hotel about more accessible rooms.