We stayed at Rossi Boutique Hotel for our February wedding and everything was fantastic! Daria was extremely helpful prior to our arrival, and tolerated all the changes we had to make, and also helped us to get a pianist for our wedding dinner which took place in the Luxury two roomed suite. Our room ( I think 24) overlooking the frozen Fontanka (an upgrade courtesy of a family member) was great - everything worked, temperature was good, bed was comfortable. (picture 19 on the hotel website). The wedding dinner was catered for by the restaurant Fiolet and was also excellent and brought to the suite.
Members of our party (who are well travelled) expressed views such as "the best hotel" "the best massage" - in the spa. Honestly the helpfulness of the hotel staff and the lovely accommodation, as well as the great location for walking to shops, (including the army surplus where we got amazing hats, and the skating on the river below!) made this trip totally perfect. All staff were helpful, but I have to mention Daria particularly we were trying to arrange this from very far away (Uganda) and had lots of issues with visas and flights which meant changing dates more than once. The Spa was the icing on the cake - yes the free sessions for residents are very early, but the prices are good and the service excellent, so don't miss out while you're there. Would I stay again? Absolutely.
Overlook the Fontanka with an upgrade from Standard room, you won't regret it