I'm glad You did not like soviet Palace of Culture. It's amazing it has not been torn down. If You are still staying in Warsaw throw away guidebooks and look for some really nice places. You certainly could see Łazienki and Wilanów Palaces, but definitely visit the Warsaw Uprising Museum (1944), see the Visitation church on Krakowskie Przedmieście and walk down to the river to University Library and Kopernik Centre (see the gardens on their roofs).