Psiri is an up and coming district of Athens, full of stylish cafés, bars and small shops.
You can use the Monastiraki subway station as the Psiri area is exactly next to Monastiraki area.
You can see the greek youth in crowds walking up and down in the former poor and industrialized part of Athens center. The place is full of contradictions. There are some inexpensive cafeterias which serve beer, wine and ouzo until very late at night which attract the more bohemian part of greek youth. There are also some very stylish clubs, bars and cafeterias which attract the more trendy and fashionable part of greek youth. And there are also expensive restaurants with live music which attract older crowds. All these people are crowded in the small and old pavements of Psiri among an industrialized environment of the past decades. It is worth visiting if someone wants to see how greeks spend their nights out and is right next to Monastiraki so it can be included in a walk in the Athens center.
There are a lot of restaurants with live music but bear in mind that they can be quite expensive. Even the restaurants without live music can be expensive so check the prices before you enter a restaurant in Psiri especially if it looks very stylish and trendy.
There are many great clubs such as ENVY, Candy Bar, Saloon Oriental, Venti, Fetish, Luv, Liosporos and many smaller ones.