One of my favorite things I have seen at weddings is the "date night jar." For this idea, the guests write date night ideas on popsicle sticks that are color coded by cost. The bride and groom can either have a jar of each color of sticks and a single jar for finished ones on the gift table, or they can put a mason jar and a set of sticks at each guest table.
As for color coding, there are generally 3 colors one for free date nights, one for cheap date nights, and one for more expensive date nights that take more planning. At the end of the night, the bride and groom usually end up with hundreds of different date night ideas, while the guests had something to keep them busy while they were waiting for dinner to arrive! Later on, when the newlyweds are looking for a date night idea, they can pick from the ideas their guests wrote down!