My daughter spent a week in Dublin this past March with some of her college buddies. Here are some of her recommendations:
(1) The Guinness factory tour (lots of tourists, but she and her friends enjoyed it).
(2) The National Gallery of Ireland
(3) The Irish Whiskey Museum (across from Trinity College)
It’s been many years since I visited Dublin myself, but I did go to a performance (The Merchant of Venice, I think) at the Abbey Theater: https://www.abbeytheatre.ie/