I have a few thoughts as someone now living here.
First and foremost - Rathdrum!! Oh, yes! I spent a fantastic 8 days there, then used it as my home base for 5 weeks (I met a generous Irish couple in Spain who said "use our garage apartment in Ireland as your home base!" so I did!). There is great history, hill walking, craft, fishing, camping .... Rathdrum is a very cool place. And you can get in/out of Dublin by train very easily (we did for the Dublin HorseShow, one day - easy as pie!) or other nice places to visit like Dun Laoghaire (pronounced dun leery) or Howth. If you're in to Ballykissangle the filming was nearby..... lots to see, there!
I'm VERY apprehensive about your thoughts on driving. Yes, Google maps shows, for example, Galway to Belfast as 3 hours 48 minutes. But, seriously - you will take MUCH longer. And I don't just mean the 25% someone else suggested in the replies, which is true, but really - once you get here, you'll hear about a castle ruin "right on the way!" and want to stop there; a pit-stop in a great pub for a coffee or a lunch, and then next thing you know you're spending the entire day in a car! You do realize one of your days (Galway/Cliffs/Dingle) shows almost 200 miles?!
I spoke to 3 ladies last night who own B&B's near my area, and they all concurred that "the first time an American stays with us, it's one night. They get here at 8 pm and then leave early to go somewhere crazy like the Cliffs of Moher the next day!! Then they come back the NEXT year and stay 2 or 3 nights when they see what's nearby!" I quote that for South Kerry, yes, but i can assure you, owners of B&Bs in Mayo, Kilkenny and County Cork are probably saying the exact same thing.....
Another thought - look at the driving as if you're in the USA. Imagine a vacation where you went to NYC, drove to Washington DC the next day, spent the night, got up and drove to Richmond, then the next day Atlanta.... sure, Google maps says you can do it. Sure, if the traffic is non-existent you may well do it. But would you experience it?? ANY of it!!!? Nope!
Slow down a bit, and enjoy the experience! The real Ireland isn't at the Cliffs of Moher with 1.7 million other tourists; it's in Rathdrum, and other small villages and towns that have much to be discovered!
Susan
ExPat in Waterville, Co Kerry