Ahhh, the wedding map. It is becoming somewhat of a dinosaur with the dawn of GPS isn't it? Although it has become a "nice to have" I am still a fan of this particular enclosure card. Not because it is something that will be indispensable for your guests... It is just a card that has the potential for such personal detail, it can easily become a nice complement to a keepsake quality invitation suite.
Please consider having your stationer develop a map to complement your wedding materials! It might become the talk of your guests...
