Hi,
I'm currently living in a place called the Boghill Centre, in Lisdoonvarna, county Clare (Ireland). I think this place is worth a post (at least !).
This is a kind of hostels were they offer Irish music workshops. These workshops are aimed to any level of playing and all instruments of Irish music are welcome.
Sonja O'Brien is the teacher, she's a brilliant fiddle player. She sometimes invites local musicians to answer questions specific to each instrument. I would say the workshops are nice for beginners and medium players.
If you look for nice sessions, the Roadside tavern is amazing: http://www.roadsidetavern.ie/roadside/asp/page.asp?p=1
Doolin also has a lot of nice pubs.
I recommend this place: nice atmosphere, nice landscapes, nice music, and very peaceful.
Also, the county Clare in itself is worth seeing...
I leave a link, if some of you are curious: http://www.boghill.com/