Celtic music is my very favorite!! We just saw the Chieftains in concert last week with the Columbus Symphony Orchestra; they've been around for about 48 years. Clannad is another favorite. Saw Celtic Fiddle Festival in concert a couple of years ago. Dublin, Ohio has an annual Irish Festival in August, one of the largest in the States. Lots of music, dancing, fiddling, games, food, it's wonderful.
Too many wonderful groups to list.