Christmas Boat Parade. This one is bigger than the one in Naples (see yesterday's post, Cheap Date Idea #23), but you can do both since Newport's is 5 days long, 12/16-12/20, running 6:30 - 9 PM every night (check online for the schedule and route) Newport Beach can get quite congested, so going during a weekday may be more enjoyable.
UPDATE 12/20: For the grand finale on Sunday, free fireworks go off at 9 PM near Balboa Pier.
Approximate cost of creative date idea = Free plus parking.
Actual value of the cheap date idea = Priceless.