I'm a mix like you, patteemom -- a bit of everything including Irish. We still celebrate the day. Because we home school two of our DKs, I've used the day/week to teach about green things, rainbows, Ireland, St. Patrick, Celts, Dr. Seuss (Green Eggs and Ham), folklore (leprechauns), etc.
I found a record album (yes, an actual vinyl record! Good thing I kept the old turntable!) of Irish music at Goodwill a while back, and I'll play it during dinner. I either try to make something traditionally Irish (recipes from the internet) or serve green foods that are supposed to be green -- I don't color it green if that's not it's usual color, or the kids won't eat it.
For breakfast or a snack, we'll have Lucky Charms cereal (usually banned for being too sugary!).
We have a visiting leprechaun during the week (thanks to ideas from OC!) who leaves chocolate gold coins, green bead necklaces and other little trinkets and causes general mischief (green toilet paper, green bows on stuffed animals, puts the bags of breakfast cereal in the wrong boxes. . .).
Otherwise, around here people usually wear something green or a "Kiss me, I'm Irish!" button and wish each other a Happy St. Patrick's Day. No parades, no day off school.