I would say the classiest container in which to have a beverage would be a close battle between a crystal wine glass and the Holy Grail (OK, probably not THAT close).
The second classiest would probably be a close battle between that same crystal wine glass and the Pampille Glass concept designed by William F. Boujan.
This elegant cup is more of a half glass than anything because it has no stand. The base of the Pampille glass is replaced by a beautiful dangling Bombay Sapphire. While being held, the jewel hangs for all to see and while placed down, the cup simply rests on the flat bottom surface.
A lovely little design to enhance the formal environment.