What would you do in Ireland…?

Check out the RS tour one-week itinerary for a start, and refine considering your own tastes (also whether you'll have a car or be taking trains.) In Dublin I loved the National Museum of Ireland and the Chester Beatty Library. The Irish Emigration Museum and Kilmainham Gaol are excellent to feed you some history. Hopefully you can leave the city long enough to see the green hills, the sheep and a castle or two.

I would head straight to Kinsale for a day or 2. Then the ring of Kerry, next Dingle and if time was left the Cliff of Moher and end in Galway.

A day in Kilkenny.

Enjoy craic, enjoy a pint of Guinness at Kehoe’s, see Newgrange, visit the Immigration museum, wander about Glasnevin cemetary, theatre at The Abbey and find a bench in St Stephen’s Green and people watch. Then again, in December, the latter might not be the best choice.

--I would do one of the shorter heritage walks (Westmeath Way, North Kerry Way, St Kevin's Way etc.) for a couple days
--Dingle Peninsula
--Galway
--Aran Islands

I have already done Dublin, Northern Ireland, and County Donegal, so I would focus on the southern Republic if I had that week.