Winter is a beautiful season. It's peaceful and calming and would make a wonderful theme for any event. People usually relate winter to Christmas which is the happiest time of year. If the funds are available for special affects maybe throw in an artificial snow machine.
"Passion of the Carribean," is a fantastic theme for a Ballroom Dance Recital. The heat from the sun and the fluid motion of the water coincide perfectly with dancing.
You could always use a classic movie or a classic book as the theme. Casablanca, Gone With the Wind, Wuthering Heights, and Jane Eyre are a few classics i could see being used as a theme.
