The daddy of all stag dos is beginning to get a bit tired of it's offspring. Stags are no longer the darlings of the Dublin tourism industry and pretty much all the best pubs and clubs along the famous Temple Bar have banned them. If you do head for there, I'd tone it down. Stag horns and beer guzzling are more likely to elicit snarls than laughs these days. We'd suggest heading to alternative towns in the Emerald Isle where the welcome is still warm.
Outside Dublin there are fantastic outdoor centres that make full use of the terrific countryside offering kayaks, Canadian canoes, sailing, windsurfing, clays, archery, quads, climbing/abseiling and horse riding.