Hello - I just completed a 3-day Dublin and 2-day Killarney adventure. I thought I would share some of our learnings. We had 5 adults from the US, and not super picky on restaurants. Tips:
Kilmainham Gaol - Tickets are tough to get 30 days prior. However, day of tickets open up at 9:15am on their website. We were able to easily book, and multiple times were available the day we wanted to go.
Driving - it really wasn't bad. We rented a car at Dublin airport and drove to Killarney and the Ring of Kerry. It took a little getting used to but overall wasn't bad. Roads are narrow, so get the smallest car that will fit the number of people you have.
Ring of Kerry - Follow the guidance Ring of Kerry Route Ye'll LOVE (+ Google Map With Stops) and you will have a great time. We drove counterclockwise and didn't experience any busses on our day. We lucked out on weather with no rain. Highlights included Rossbeigh Beach, Kerry Cliffs, Coomakista Viewpoint (Sheep!), Portmagee for lunch (Skellig Seafront Cafe), Derrynane Beach and the Ladies view. This was about an 8-hour day with time at each stop. Tip: Make sure to go up to the Coomakista viewpoint. From Kerry Cliffs, it looks like a dirt road and super steep but isn't that bad. Take it slow and you will have unbelievable views. This was a surprise highlight for us.
Killarney Restaurants - Tango Street Food for pizza is a must. Make a reservation. It was so good, and one of the top 1-2 meals we had on the trip. Someone on the forum had raved about this place and it is true. Staff was great. Coffee at KP3 had a great staff and just wandered into many bars.
Dublin Restaurants - get reservations to most places. Bambino Pizza for a slice was great. Don't worry about the line - to the corner is about a 30 min. wait. Matt the Thresher was good and had fun drinks. Gallaghers Boxty House in Temple bar was full of tourist but the corned beef was excellent. The Ivy (I know, many will disagree, and it was expensive, but we had a very good meal there - get the salted caramel Espresso Martini and Shepherd's Pie), Metro Cafe for brunch or lunch.
Bars - We enjoyed Temple Bar (yes, very touristy and drinks are more expensive), but really liked other areas as many of you have mentioned: The Hairy Lemon, Peter's Pub and many more in the Grafton Street, Stephens Green area; Toners and many others on Baggot Street. Raise a Guinness and "split the G"