Some years ago we stayed in what was then the Great Southern Hotel near Rosslare Harbour, and it was really popular with families. Friends of ours that were also staying there had their 1 1/2 year old twins being minded in the creche for a few hours every day, meant they could enjoy dinner on their own!
It's now called the St. Helen's Hotel, but from what I hear the facilities for families are as good as ever. Kids under 2 are free, they can arrange babysitting. Midweek specials at the moment are about €90 each for 2 nights and 1 dinner, and not much more for 3 nights.
As it's only a couple of hours drive from Dublin it might be an idea?