First, get the RS Ireland guide and read it. Seriously, makes planning so much easier.
Secondly are you flying into Shannon and out of Dublin or returning to Shannon?
In Dublin if you must then do the booze tours of Jameson and Guinness breweries but SO much more too see and do
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I suspect there's a huge age difference between you and I so what would be of interest would most likely differ.
However, you asked so I'll offer suggestions. Book of Kells at Trinity College, The Post Office to understand the Easter uprising, Kilmainham Gaol, (prison), Powerscourt Estate (outside Dublin), sitting in St Stephen's green people watching, seeing whats scheduled at the Olympia Theatre and Abbey Theatres while you are there, an visit to the fishing village of Howth for the seafood chowder at Tram Chowder stall at the Howth Market.
Personally I'd spend far much more time on the West Coast. Dingle, Slea Head, Gap of Dunloe, Killarney National Park,
Kinsale. I'd drop Cork and go for Dingle. Pint at Foxy John's. Climb up the path next to Coumeenoole Beach for a stellar view of the Blasket Islands or seeing them from Dunquin Harbor walled pathway. You didn't mention time of year so if you wish to see the Blasket Islands or Skellig Michael you'll need to check ferry service times. I'd also drive in and around Gougane Barra Forest Park outside of Kenmare. St Finbar's Oratory is a favorite for weddings. I also like the Kerry Cliffs better than the Cliffs of Moher because I like the drive to Portmagee. Less tourists.
Just remember you'll be driving on the opposite side of the road than you are used to, that most rentals are stick shifts and that you'll need Euros. Have driven the island 3 times in 20 years. Truman was President when I was born so from experience I say get the smallest car possible, as the back roads are teeny tiny. Cough up the cash for the GPS and purchase all the car insurance you can.
Lastly use, Google maps satellite view to look at routes and to see what I mean about small roads. Beware of sheep, people out walking their dogs, riding bikes, lorries, farm equipment.....in other words...Don't rush while in Eire. Its' all about slowing down, the beauty, the people, the music and the Guinness.
Slainte!