What do you like? It is easier to give advice if you give some specifics. Like with every city trip, there is always more to do than you have time for. So you either can stick to the list of highlights google gives you, or only look into the aspects that interest you.
- If you like to drink, you can't leave without having a guinness.
- Irish ancestory? The emigration museum.
- Into Game of Thrones, look into the film locations.
- Like art? Go to the National Gallery or the IMMA.
- History buff? Plenty of castles and the national museum.
- Love nature? Great views all around and a national park nearby.
- Want to kiss the Blarney Stone, it's 3 hours to the South by car.