Cook a meal (If can't cook, just order take-out) and set the mood with candles, music and champagne. For dessert, serve up something sweet, like chocolate cake or chocolate covered strawberries.
Dinner at a Nice Restaurant
Make a reservation for two at an elegant restaurant.
Plan a trip for out of town just for the two of you.
Go see a romantic movie at a drive-in theatre.
Put together some photos of the two of you and go through it together.
Get a couples massage or go to a spa.
Plan a romantic walk along the beach, in the park, or to some meaningful place. Leave your phone at home or turn it off.
Plan a fancy picnic with nice plates, silverware, cloth napkins, and glassware (for the champagne).
Breakfast in Bed
Suprise him/her with breakfast in bed.