We spent a fantastic week at Cristiana's. The Palazzo apartment is indeed stunning - this is definitely the best lodging Venice can offer ! Beautiful high ceilings, lovely muted colors, a lot of great art on the walls, a balcony on the canal from which you can see the gondoliers passing by (you can hear them too, sometimes a bit early in the morning, but this is fine ! ) and such refinement in every detail.
You can also see right away how much care has been taken by the host to make you feel welcome. The information and advice come in four languages (even Russian !) and there are plenty of nice touches everywhere : lists of restaurants, two kinds of extra pillows, umbrellas and raincoats (we didn't need them, the weather in October was perfect), plus piles of books, essays and even novels about Venice. I read a few at night in my very comfortable bed, I just wish I could have read them all !
But the best is definitely your host, if you have the opportunity to meet her : Cristiana is wonderful - she is such a warm, generous, interesting and cultured person. She obviously loves the city and she is so knowledgeable about it, it was a great pleasure meeting her and I felt very lucky to learn so much about Venice in such a short time. I just hope to be able to go back again and learn even more !