I visited the folks in Longford with the kids this year. There are parades in most big towns for the kids. The big parade in Dublin is always tourists and families ( you can usually spot the tourists by the vegetation stuffed into a shirt or jacket pocket, not many Irish people do that)

For most Irish people, it's just a paid day off work, with some going out drinking with friends and others like myself it's a day where the creche is closed and there are little creatures to be entertained.