Send them to the opera for the night or purchase tickets for the symphony if that is more their style. Or, perhaps they would prefer tickets to the theatre to view a play or a musical, like Cats or Oz. You can also give them tickets to the latest art show or charity event or they may appreciate tickets to a winery tour. Consider giving them a pair of tickets to a recurring event the couple enjoys such as a baseball, football or basketball game where they can root their team to victory. Or perhaps, they would prefer tickets to see the American Idol Tour, Dancing With The Stars Tour or a concert group on tour.
A romantic hot air balloon ride which includes a champagne lunch is an unusual gift they might enjoy or send them on a dinner cruise around the bay where they can dance under the stars. Schedule a horse-drawn buggy ride for the happy couple to attend on their one month anniversary, along with an intimate dinner for the two of them at their favorite restaurant. You could also prepay for a specialty brunch or high tea at a five star hotel and include a spa treatment for after the meal.
Although they probably already know how to cook, send them to a gourmet cooking class or a lesson in wine appreciation, where they can meet similar couples who share their passion. A couple introductory dance lessons at a studio will have them dancing cheek to cheek, while a class in photography gives them a new perspective on taking vacation photographs along with a new hobby. Another option is flight lessons, so they can take short hops to neighboring cities for short, romantic get-aways together.
You may also consider making a gift for the couple. Some examples include a coffee table photobook of pictures from the wedding, or the activities leading up to the wedding, like the rehearsal dinner, bridal shower or bachelor party. Consider drying out several flowers from the bridal bouquet and creating a shadow box which contains the flowers, invitation and a picture of the happy couple during the wedding. One last idea is to offer to assist them in preparing the invitations, doing the table centerpiece or cooking the wedding cake, if these are talents you possess.