Alas, I believe the Irish pubs no longer permit smoking, or so I've heard. A fine point, but an important one, order your Guiness anticipating a wait. A good barkeep will draw a pint with precision, allowing the head to develop, so don't be a damned tourist and inquire why service isn't more snappy. Often, there's a nice spread of food on offer while you wait. I've heard the Peterson store in Dublin is worthwhile.
I thought the library with multiple balconies and ladders to book shelves, and the exhibit of the Book of Kells, illuminated manuscripts, were remarkable. Trinity College where they are located has a wall around it, so you may have to walk a way to the entrance, but it is worth it. St. Stephens Green, Dublin's Central Park, is an escape on a pleasant day. By sheer luck, I encountered the 150th birthday of Oscar Wilde at Trinity College and heard a reading by his grandson who looks a lot like him. I waited with other walk-ins while they opened extra seating for the overflow.
St. Patrick's Cathedral where Jonathon Swift was the Dean is Irish-Anglican. The Dean is buried there, amazingly beside a longtime woman friend who perhaps was his consort. Imagine that happening today. Huh.
We also went up to Sligo to William Butler Yeat's grave where he also lived in a medieval tower with his new wife and children during the troubles in the 1920's. My late wife looked around their stone tower bedroom and said of his wife, "She must have really loved him."