Some activities for a wedding reception would be to have activities for the little and young ones, like activity placemats. Activities for the could be placecards with fun questions to answer about the bride and groom. You could also have placecards with fun facts about the bride and groom. With placement cards you can have fun with it, one idea is to make them into a universe/night sky sort of layout, such as having a background of the universe/night's sky and planets/stars for the amount of people that have on your guestlist. Connect the planets/stars according to how everyone is related. On the back of the placements cards you can have a short love story of how the bride and groom met and fell in love.
Hope that helps