Id do the hop on and hop off if you were feeling particularly lazy or not good at finding your way around.. It can be a bit dizzying the first time around..
I can second the Porterhouse. Excellent beer and food. Always lively and we used to eat there once a week. I also recommend getting a few drinks in at
Sin è (north of the River) and at
The Long Stone and
Messrs Maguires , who are both JUST outside the Temple Bar are and really nice to drink at.
Guinness is GREAT. Very laid back and you do want you want (or can wait for a guided tour) Jamesons was okay, but when we were there (about 5 years ago) its was a bit dated and meh. We went to see the
Book of Kells at Trinity College Dublin. I recommend hitting up the
Metro Cafe for breakfast for one morning. So, so good.
Id avoid drinking directly in Temple Bar, as its complete rip off and just too full of tourists, IMO and was just not pleasant.
If you want some retail therapy, head over to Dundrum via the Luas (tram) line. 15 minutes from St Stephens Green. If you use either line, youll need to purchase your tickets BEFORE you boards as theyre not sold on the tram. There is a mall AT St Stephens Green, but its ghetto and crowded.
Enjoy your trip. I lovelovelove living in Dublin. Such an amazing city