E.A.
For a "short" trip like that, I head to the greeting card section of the store and pick out a different card for each day - some funny, some sexy, some romantic. Then I write a short note in each one - a favorite memory, something I'm planning on doing when he comes back, etc. - and label the outside of the envelope with the day that it's supposed to be opened (or, alternatively, write the mood of the card). My husband loved this when he would have National Guard duty.