I usually post this with the question, but since I didn't I will add my favorites from my past experience:

Co workers from company:   We did the Godiva Chocolate as well (truffle box was my favorite to pick from)
Co workers on a personal level  - Tree ornaments, or a magnet for those who do not celebrate Christmas.
Boss -  Something personal -  For a Golfer, maybe golf balls, For a fly fisherman, fly box, I would put some thought into it.
Clients - Gift baskets, though I never had to send out client gifts.