My husband and I often kiss, hug, etc., in front of our kids. We don't like make out or anything over the top, just don't hide our affection for one another, either.
My MIL was over the other day and my husband grabbed me and kissed me with a loud, exaggerated, "MUAH!" as he did so, making me laugh. The kids, who are all elementary age, were in the room and they started groaning or giggling and saying, "Ew, gross!"
MIL looked like she was going to pass out and said, "Don't do that in front of the kids!" DH asked, "Why? Shouldn't they see us loving each other?" She said, "NO! That's NOT appropriate!"
Do you and your DH/SO show affection in front of your kids?