My bosses have frequently been out on business trips on Bosses Day. When that happens, I usually get them a potted plant and a card and leave it in the office for them to see when they return. (Probably doing this again this year.)
On year, I arranged for a gift basket to be delivered to the hotel room where he was staying. That was when I only had the one boss. He was on a trip with several other people, who were also bosses, and none of them received anything from their Secretary. He really had fun with them about what a great boss he must be.
Another great Bosses Day gift idea is a coffee cup with some candy or gourmet coffee packs in it, all done up with a nice ribbon, of course.
Hope these ideas help.
JusPeachy 
