Mostly quiet. Though I am not opposed to public hand-holding, snuggling, and kissing (within limits), and telling people I love them-- whether in public or in private. I'm not going to paint it on a billboard, though. My husband and I both say "I love you" to each other often, and also to our kids. I'll yell it across a parking lot if I really feel the urge, though my husband prefers the quiet "I love you" hand signal that he picked up from his parents and taught to me (holding out thumb, index finger, and pinky, to make the letters "I L U").

Verbal affirmation is very important, though it should always be backed up with loving actions.