The magic to a great meeting is all of the work that's done beforehand.
Meetings should have as few people as possible, but all the right people.
I just find that people can waste a lot of time in meetings, so I try to restrict meetings to the minimum that they need to be. But I have lots of time in my day where I am available to have informal conversations, where I grab someone to talk, and people can just walk up to my desk and talk to me.
Meetings should be great - they're opportunities for a group of people sitting together around a table to directly communicate. That should be a good thing. And it is, but only if treated as a rare delicacy.
The majority of meetings should be discussions that lead to decisions.
Contrary to popular wisdom, the mark of a great meeting is not how short it is or whether it ends on time. The key is whether it ends with clarity and commitment from participants.
The problem is too often they are boring, and boring in a meeting happens for the same reason as in a book or movie - when there is not enough compelling tension. Meetings should be intense.
The success of a meeting often depends on having the right documents - proofs, artwork, schedules, research charts, etc. - present at the start of the meeting. All too often we arrive like plumbers, leaving our tools behind.