I don't do the whole corned beef/cabbage/veg thing unless my inlaws are around. Kinda bland. I think the previous suggestions for stew if it's cold, or fish and chips (you really can't go wrong with that) are good. We like to do reuben sandwiches on St Patty's day because it's more "flavorful" than just the corned beef and cabbage. We get dark dark brown bread (is that Jewish Rye? Or more likely Pumpernickel?) and butter the outsides like you would a grilled cheese. I put sliced corned beef (from the deli, have them slice it up for you as the packaged stuff just isn't very good), some kraut, a slice of swiss, and cook it just like you would a grilled cheese. We don't do dressing because it's fat for no reason, and the butter, sauerkraut, swiss, and meat are loads of great flavor. No need for anything else. We slice up potatoes and make our own "fries". We also love Irish Bananas (ha--there's nothing Irish about bananas really, but whatever): we melt 1/2 C butter in a skillet, stir in 1/2 C Irish whiskey and 1/2 C brown sugar and bring to a boil, stirring until sugar is all dissolved. Then add 4 bananas sliced the long way and simmer them until they are tender and glazed with the syrup. Serve the bananas immediately with vanilla icecream. It's a totally "Americanized" Irish dinner, but we love it and really only serve it once or twice a year. It's fun.
Last year we did this for dinner, but for breakfast we served green eggs and hash (scrambled cuz that's how I prefer them, with food coloring), I cut the toast like shamrocks. We also made a leprechaun trap (got that idea from Family Fun magazine): we didn't succeed in catching him, but he thought it was a good try so he left a gold coin but it turned to chocolate because he's a tricky fellow. My son is sure we'll do better this year.