This tip is about beer I enjoyed in a few evening/night pubs in Warsaw. All pubs mentioned below are described in details in my restaurants tips.
There are many reasons to choose Polish beer in Warsaw. They taste good or very good. Futher, imported brands of beer are more expensive and available in limited choice. Many pubs have a deal with one brewery and offer brands of this brewery at lower price than the others. However sometimes the choice is limited to brands of the one brewery, like in Piwna Kompania: Tyskie and Pilsner Urquell only.
Polish draught beer, being both good and the least expensive is the most often ordered. Thus in busy pubs there is no risk to get unfresh draught beer, I mean from a barrel opened the previous day (or week) and not properly stored (in +4C) at night which is quite common way of saving on energy, right?
In wentertime you may try warm or hot beer (piwo grzane) usually served with some spices and herbs (dried cloves) and with raspberry sirup added (often on request).
If your native language is non-Slavic do not try to pronounce very difficult names of Polish brews unless some local helps you to do it right or almost right. Write down the names and show your bartender or waiter.
MY TOP POLISH BREWS
1. Zywiec is, in my opinion, the best of Polish brew, maybe except some locally available ones. Zywiec Jasne Pelne (5.6% alc., Zywiec light full) is premium lager beer (somerhing between pale lager and pilsner) with light gold colour and grassy, slightly herbal (thyme, sage ?) notes. If you choose Zywiec in a bottle there is beer thermometer on the back label to let you know when the brew is at the appropriate temperature (exactly +4C). Essentially, there is a small white box on the back label and when the beer is at the appropriate temperature, a gold Zywiec logo magically appears. Warning: bottle opener is needed to remove the bottle cap, do not try to twist it :-).
Dress Code 2. If you like strong, sweet and bottom-fermented brew choose (my wife's favourite) Zywiec Porter (9.5% alc) which is a Baltic Porter, top fermented lager in fact. It's dark brown pour with red highlights, very thick, very creamy. The flavor is great, roasted malt, lots of bitter chocolate, coffee, prunes, toffee, raisins, plums, and slight notes of smoke.
3. If you like light pilseners with very delicate bitterness and taste (American in style, or as some malicious folks say watery) try Tyskie Ksiazece (5.7%) brewed in the oldest in Poland, still operating brewery run by Kompania Piwowarska in my hometown, Tychy. It's the most popular beer brand in Poland and among top 10 in Europe (by sales), the least expensive as well. This clear yellow beer (urine for fans of Zywiec :-) has no aroma and delicate grainy and lemony taste.
4. Okocim Mocne (7.1% alc.) brewed in Brzesko (southern Poland) is typical for Poland European strong lager, stronger versions of pilsner. This orange or deep gold beer has very sweet aroma and simple, sweet malty flavour.