Driver for a Day! Follow the "Uber" example; include one or two private drivers for a day as a silent auction item.
Whether purchased as a ride to get the kids from school to all their daily actvities or a treat for a day out on the town for mom or dad, having a driver for the day can be just the ticket. Flaunt the luxury of not having to worry about parking and not having to rush from one pickup to the next; having a driver for a day can be a real treat.
If you have several available drivers, try targeting the audience for each driver. If the item is targeted towards parents who need a "day off from driving" throwing in a simple addition - such as a stop at Cold Stone for a surprise treat, can be that "cherry on top" that makes the deal. If instead the item is being presented as a ladies treat, why not include a special bouquet of flowers at pick up? These small additions can help make this an extra special item that your bidder will not want to pass up.