Oh man, I was in Ireland last June and had a great, great time. I was there with a friend, so it was more of a girl's trip, but I'd love to go back for a honeymoon and do a lot of the same things.
We spent 5 nights in Dublin, 4 nights in Killarney, 3 nights in Galway, and 1 night in Shannon. In Dublin we did the usual things.....Guiness Storehouse, the Jail, Dublin castle, Trinity College/Book of Kells, St.Patricks, Christ Church, etc. Highly recommend doing the musical pub crawl tour---it's touristy but fun. We also took a day trip to the Wicklow Mountains. Very fun.
In Killarney, we did a lot of outdoor stuff. We spent a day hiking the Gap of Dunloe and then had a boat ride through the 3 lakes. This took all day, but it was so much fun and there were beautiful views. The hike was around 7 miles. We also drove the Dingle Penn. We also did a Killarney National Park one day. We stayed at a place a mile or so out of town called Kathleen's Country House (I think....it was Kathleen's something). It was a pretty cute little inn. The hostess was pretty nice and fun. I'd recommend it.
In Galway, we did the Cliffs of Mohr and the Aran Islands. We did a bike ride around the island. We also toured the city and saw a church where it is believed that Christopher Columbus stopped at before heading to America.
We planned our trip in about 15 minutes, but we both wouldn't change much at all about the trip. We loved the amount of time we spent in each city. I definately wouldn't spend more than 3 nights in Galway. We really focused on stuff that we could do outside of the car, so that the person that was driving could enjoy it. We didn't do the Ring of Kerry b/c we were worried about driving it, but I've read that Dingle is better anyway. One thing that we would do more of if we went back was stopping in the different little towns we drove through. The driving was a bit stressful and we were always wanting to get to our destination. I think if either of us went back, we would feel better about stopping in different cities. To save money, we would eat breakfast at the hotel/inn, buy a small snack at lunch time, and would eat an early dinner. Most restaurants would have a 3 course early bird special for around 20 euros.
Some things that we were glad we did was eating at nice restaurants and not eating crap (don't get me started on a trip to Italy where TWICE we eat at some crap restaurant b/c we were to tired to go to a good one). We were glad we didn't pack too much into each day and that we didn't focus on seeing everything, but seeing what we did see WELL. We were glad that we did a lot of the outdoorsey stuff too. We stayed at a kind of crappy hotel in Dublin (but in a good location) and a small inn/B&B in Killarney, our hotel in Galway was a nice, modern one and it was nice to have a big, cool, room with modern stuff and lots of TV stations towards the end of our two weeks.
As far as your GPS question.....I bought a Europe map before going to Ireland and it worked very good for us. It got us lost a few times, but we always found our way.
If you have any questions, feel free to ask me. We really did have a great time.