80 is a big birthday. I think I would chip in together and get a beautiful floral arrangement to surprise him when he comes into his office. That will make him feel special. Then he can either take it home or enjoy it at the office all week. When I would get flowers at my office, I usually put them out where everyone could enjoy them after a day or so.

With that plus lunch plus cake, I don't think you need any other decorations or small gifts. Especially if there are more than just a few of you, you can get a really impressive arrangement.

I think men especially appreciate flowers because they don't get them as often as we do. But everyone enjoys the luxury and beauty of a gift of flowers.