We loved Locanda Orseolo but if quiet is your highest priority, I wouldn't recommend a canalside room. Well, perhaps it would depend on the time of year/weather. We had a room overlooking the canal and chose to keep our windows wide open in late April. Some nights were noisy, others were fine. Perhaps if you kept the windows and shutters closed, you'd be OK. I'm a light sleeper but preferred the fresh air over quiet. We would choose Locanda Orseolo again but would most likely ask for a room facing the courtyard.

We stayed at Locanda Orseolo in May and it was fantastic.We had a courtyard room which was very quiet.
My brother and his wife had a canal room which they said was interesting for the view but noisy for sleeping.

It has heaps of charm, great staff, good location being really close to San Marco but tucked away so you feel you are miles away from all the hubbub.

Thanks very much for the replies-- they are helping so much. Quiet is more impt to us than view, so we would definitely ask for courtyard. And the standard rooms would be too small, so we'd ask for superior. Problem is that superior rooms are listed as having a tub, and we're shower people. (Don't even remember last time I had a bath.) Can any of you tell me whether the "tub" rooms have the shower/tub combo, or if they're literally just a bathtub? Also, is there adequate cover, i.e. so that water doesn't go all over the floor?
Thanks once more.

The staff at LO responds readily to email. Why not ask them about the room? (Our superior room had a large shower, no tub).

Our room had a tub with a shower in it, with the detachable hand-held kind of shower. There was no problem with water on the floor.
The bathroom was actually quite spacious and lovely with a big window that opened onto the courtyard.

I'm sure our room was just a standard one but had plenty of space.
If I can find where I wrote down the room number I'll post it here.

No amount of money is going to guarantee quiet in Venice. You must have someone with lots of recent experience provide you with a specific room number to be sure. Specific rooms are rarely guaranteed. (It helps if you're a regular visitor.)

King beds are not common in Italy. Have you ever carried one up a narrow, ancient, winding stairway? For a room (large enough to hold one) with a quiet view, you will need at least $1000 a night.

If the room you're given is near any water, you're going to hear motorboats. Working Venice works at all hours. If your hotel is near a school, your going to hear screaming children. If your room overlooks a busy campo, you're going to hear people frolicking at all hours, especially the drunk tourists and young lovers. If your room overlooks a well-used calle, linking one busy area with another, you're going to hear the sound of shoe heal clanking off a stone echo chamber, also at all hours.

Busy, popular cities in Italy are no place for people seeking quiet. Big cities are much too alive for that request. Earplugs and Xanax work wonders.

I forgot to add, if your room is anywhere near a smoker's habitat, be prepared for a nagging round of smoker's cough as early as 4 AM. The sound of emphysema seems everywhere in Italy these days.

Take a look at Foscari Palace. It's very elegant, rooms were very nice and the bathroom was to-die-for! Our favorite hotel in Italy. I remember it being very quiet and private.
It's right next to the Ca d'Oro vaporetto stop, so getting around is a snap.

Breakfast was included...eggs, bacon, toast, etc. They have "soirees" a couple of nights a week for guests...free champagne, canapes, music. A nice way to relax before dinner.

http://www.hotelfoscaripalace.it/

One note to throw into the conversation about a quiet room. When we arrived in London the first thing we did was go to a store and buy a European voltage fan. It was about 12" x 12". We also bought a set of adapters to use it in Switzerland and Italy (other stops on our trip). We used that every night and it GREATLY enhanced our ability to sleep with the added noise (or the extreme quiet...can't sleep with either). We left the fan at our last hotel. Next trip we'll do it all over again.