Dublin is nice, but it pales in comparison to the rest of the country (IMHO).
It is a beautiful drive around the Ring of Kerry and the Ring of Dingle (Slea Head Drive). Conor Pass is a must see in my opinion. We stayed in Tralee and used it as a base for a couple of days. We were fortunate to have a clear day at The Cliffs of Moher. Durty Nelly's in Bunratty is a good place to have a beer and a good meal. It is right beside Bunratty Castle. In the North, the Giant's Causeway and the Carrick-a-Rede bridge were good stops.
My wife and I have strong ancestral ties to Scotland. Edinburgh is a good base to use. Inside Dunfermline Abbey is the burial place of Robert the Bruce. Nearby is Sterlin Castle, Bannockburn, and the Wallace Monument. Our favorite part was visiting the "castle" that adorned the cover of my wife's paternal family tree book. It was where her 14th great grandparents lived (Barr Castle). (I tried to insert a photo of it here but I'm having trouble doing that.) Melrose is a beautiful small town. The Melrose Abbey is where Robert the Bruce's heart is buried.
I could go on and on, but rest assured that Ireland, Northern Ireland, and Scotland are all beautiful and well worth the time and expense to visit.