I lived in Dublin for 2 years and it was awesome. If you don;t mind walking you can do a load on foot.
As mentioned above, hop-on-off bus is well worth it. Guiness Storehouse is a good one for a rainy day as its all indoors and a pint at the top is well deservered.
My favourite pubs for a Guiness in order of choice 😆
1. John Kavanagh aka Grave Diggers on the edge of Glasnevin Cemetry Drumcondra
2. Stags Head – Dame Lane (over the road from Temple Bar
3. The Cobblestone – Smithfield
The Temple Bar in Temple bar whilst pricy is still good fun. Also prices go up after midnight so get your pints in before then.
Train to Howth for Seafood is another good little trip.
You won’t be short of things to do