My wife and I went to Ireland last year for 16 days. We stayed in Dublin for 4 nights. Guinness was fun. We both enjoyed the natural history museum and the Chester Beatty Museum, with the latter one having some premium examples of 15th century Japanese swords (the exhibit regularly changes, but even one of the guard was able to explain all of the pieces on display with detail). The food was surprisingly good almost everywhere we went.
We did one really nice dinner out at "Dax" which was nice to see the finer dining side of things.
We basically covered the southwest after that. Glendalough was a good day trip, and we just bought some cheese, bread, and salami and did a picnic there.
Hope some of that helps.