Any suggestions on where to go for happy hour in Dams Square area?
Right next to Dam Square is the Red Light District with countless pubs. Right on Dam Square there is the large Europub bar ( http://g.co/maps/82wpg); between the dept. store and the Hotel Krasnapolsky. There are two other entertainment districts in the city with lots of watering holes as well; including Leidsplien and Rembrantsplien.
Please, do yourself a favor, avoid the run-down pubs near the Dam Square and head to the Leidseplein or even Rembrantplein areas for a nice(r) happy hour.
There are good and bad pubs in all three areas. The Europub I mentioned is anything but "rundown". In fact, when the US Nat. soccer team was in town a few year ago Budweiser rented out the place for US fans, so I have some fond memories of the place. Closer to the RLD I can recommend this place: http://g.co/maps/kx2gb Also the Stoof Pub, and the Old Sailors Pub among a few. The only place I would avoid is a pub called Excalibur which seems to be a Hell's Angel's hang-out;)