Just to add my experience. I find that in order to get better airline rates I am forced to travel into town on Saturday. So I'm in town on Sunday with little to do other than catch up on work that really should have been done before I arrived. So maybe doing more on Sunday would be a possibility.
The problem with Friday is that after having spent a week at IETF I really want to either get back home or to my weekend destination at a reasonable hour. That usually means getting on a plane by 11am if not earlier. So regardless of how important the Friday meeting is, I probably won't be attending it.
