Trying to make a reservation for three nights in late May, and all the top (reasonably priced and centrally-located) choices on Tripadvisor seem to be booked. Wondering if anyone has a little-known gem I could look into!

Have you tried Hotel Splendid? Great location and deluxe rooms are really luxirous!

I'd guess they're booked BECAUSE they're TripAdvisor's picks. So look elsewhere, past threads here and other forums, guidebook recommendations:
http://www.fodors.com/world/europe/i...ce/hotels.html
http://www.frommers.com/destinations...67_indacc.html

I've stayed here and liked it:
http://www.hotelhesperia.com/en/

Short walk from the train but still off the beaten path,some rooms with canal views.

http://www.alpontemocenigo.com/

Try this one Cathy...it's our favorite and also for several other Fodorites..well located, near a vapo stop (St. Sae)

stu

Try www.venere.com

Hotel Cannaregio Residenzia, Hotel Flora

We stayed here:
http://www.aitagliapietra.com/

We have also stayed at www.hotelgalleria.it

You could try this site:

http://en.turismovenezia.it/

My heavens, the top 3 are booked - but there are hundreds! please don't be discouraged, just do a little more homework. I like the website www.venere.com because it has a nice mapping function - we like the Dosoduro part of the city - we stayed at LaCalucina? but it may also be booked. Believe me, you will enjoy Venice so much, you won't spend much time in our room.

Look at Hotel Flora--love the location

Both www.bookings.nl and www.venere.com let you sort your search by customer review rankings. Since all customers who book through those two sites are asked to rate the hotels, the numbers tend to be more reliable than Tripadvisor's (since Tripadvisor reviews are voluntary ratings, there tends to be a higher percentage of cranks writing in, ). If you see ratings on Bookings or Venere averaging over 9.0, chances are it is a stellar property, and I've always been very happy with anything rated over 8.0 on average.

Thank you, everyone. You're right, I was not persistent enough. Will do some digging now!