Dublin pretty much rocks. Lots of good drinking to be had there for sure. And you might not expect it, but the women in the city are hot!
Everything in Dublin is pretty cool, the Guinness Storehouse, Old Jameson Distllery, The Jail/Museum (Kilhaman Goal, I think). All the good partying takes place in the old part of the city called Temple Bar, you can't go wrong there.
As far as taking an "excursian", I took an all day bus tour that went to a place called Glandalough and then to Killkenny, it was worth it.
If you have the time, buy an all day pass on the DART (Dublin Area Rapid Transit), I think it was about 8 or 9 euros. It runs up and down the coast and makes stops in all the suburban town/villages. You can get off, explore the local town/castle, then get back on and go to the next one.
Three of the coolest towns are south on the DART. Hoth, Dalkey, and Brae. Dalky is where Bono and a few F1 race car drivers live. Lot's of money.
Enjoy.