Before everyone jumps down my throat about not dedicating enough time to either country or missing the essence altogether, know a few things about me:

1. My wife and I are Americans in our late 20s. We have never been anywhere in the UK before. We are going for the first time next year.
2. I seriously don't expect to return to Ireland or Scotland for at least 15 years.
3. We are not nature people. While I am excited to see green hills and cliffs, more than a couple of days of that will be too many for us.
4. Our idea of a good time is sitting in a resturant eating/drinking in a historic plaza in a vibrant community enjoying the people, culture and architecture.

I want your honest feedback on my proposed itinerary:

Day 1- Arrive in Dublin, sleep in Dublin (3 nights)
Day 2- Dublin
Day 3- Dublin
Day 4- Drive to Cobh, overnight in Kinsale (2 nights)
Day 5- Kinsale
Day 6- Drive through Killarney and sleep in Dingle (2 nights)
Day 7- Ring of Dingle
Day 8- Drive to cliffs then to Galway and sleep in Galway (2 nights)
Day 9-Aran Islands/Galway
Day 10-Fly from Galway to Edinburgh; drive to St Andrews and sleep in St Andrews (2 nights)
Day 11-Day trip from St Andrews
Day 12- Drive to Edinburgh and sleep in Edinburgh (3 nights)
Day 13- Edinburgh
Day 14- Edinburgh
Day 15- Fly home from Edinburgh

Make sure you bear in mind that the first ten days of your programme will not be in the UK! I also think most Scots take their Scottish heritage as being more important than their place as part of the UK.

Much of your Irish programme is where people go for scenery. We are not strong on historic plazas here. You can get some approximations in Dublin and Galway.

If you get nice weather, Galway is a good place to sit outside a pub drinking and people-watching. The Quays would be a good place for that. And there are several other pubs on Quay Street that have outdoor seating.

I always want to go to Dublin, Ireland. I am really interested in Irish culture and people because I watched Irish indie film called Red Roses and Petrol in screening.
http://www.youtube.com/watch?v=JUvgLWxelDA
http://www.redrosesandpetrol.com
I want to know about Ireland.
Can't you tell me about there more???

Neither Ireland nor Scotland is big on sitting in historic plazas - the weather doesn;t allow it. On nice days some pubs/cafes will put out a few tables and chairs on the sidewalk - but most days are too chilly and or rainy.

There is lots of interesting architecture and some good and great restaurants - but primarily indoors. There are also many great, interesting historic sights.

But your description of what you want - #4 - sounds like Italy, Spain or Southern France - not Ireland or Scotland.