1. Guests often arrive with a suitcase full of unexpected items.  To accommodate their needs, include short- and long-hang rods in your guest room closet.  Someday, one of your visitors might show up with a ball gown in tow.  
  2. Do your guests tend to linger for extended stays?  Whether you plan on inviting long-term visitors into your home, or even if your frequent guests are clotheshorses, provide him/her/them with a few drawers for folded items and accessories.  
  3. Plan on storing spare linens (bed and bath) on a shelf in the guest room closet.  That way, you're organized and prepared.
  4. Just as piles of dirty laundry cause anxiety in the master bedroom, the same goes for your guest room closet.  So why not consider a friendly gesture: Incorporate a hamper or pull-out basket to collect your visitors' linens and personal items.
  5. Leave a few feet of extra space on the floor of your guest room closet for an easy storage solution for suitcases.  Or, you can buy a couple of luggage wracks that neatly fold away into the closet when your guests have officially left the building.
  6. If you decide to benefit from the masterly skills of a custom storage professional for your guest room closet needs, then make sure to discuss your specific ideas for the space.