I want to recommend Warsaw, because this is capital of Poland and there are interesting places, for example: Palace of Culture, mermaid statue, very good museums (like Warsaw Uprising Museum) and theaters (like ,,Wielki"Theatre). You can also walk through the beautiful park: ,,Łazienki Królewskie ".There are peacocks and squirrels. Ithink, that Warsaw is preety place, and is worth the command.
I would like to recommend you Cracow. it's such a beautiful old-fashioned city. In Cracow you can go for a very romantic walk through the old streets. You can also visit the 'sukiennice' and the 'mariacki' church, which are placed in the middle of the city(?). You can also visit the Franciszkańska 3 street, that's the street of Pope John Paul II. Also there are many Cinemas, Museums, squares, pubs, restaurants etc. Cracow is a great city, and it's worth to be visited, So I think it will be a good choice to recommend it for you.