I lived there too, for 10 years.. in the red light district..
I recommend..
Melkweg/Paradiso for concerts/weekend parties.. less stuck up than many other clubs. Check out the programme before you go.
Or you could go to the Escape club on the Rembrants plein..I am a bit out of touch with the rest of the club scene though.
For the more sophisticated, try The Supplier Club, off the N.Z Voorburgwal, for that lounging experience.
Hemp Museum (name shortened to avoid deletion) on the 150 O.Z Achterburgwal,
There is a Tattoo Museum on the same street ^
The Tara - Irish Pub extraordinaire - on the Rokin, just below DAM Square.. to get warm in front of a fire and have a drink and good food.
keep in mind that in a group of a dozen lads, your options may be limited.. Some clubs will refuse you entry etc.
p.s. do watch out for TRAMS, and dont get a hire bike if you are going to be riding it under the influence.. its far too dangerous!
taxis are a rip off, maybe not so bad if you are sharing.. but airport to City centre is 60 euro? Trains are very effective, as are trams for getting around town