This is a neat thread.
I was VERY fortunate to be present when the aircraft was ferried from Renton to Boeing Field.
The ceiling was below minimums for most of the morning and they didn't know if they were going to be able to fly that day - the B-17 didn't have any "modern" navigation gear in it and the FAA wouldn't allow the aircraft to be flown in anything but VFR conditions.
I don't recall what time it happened, but when the runway lighting was turned off, cheers were heard because it meant that the ceiling had lifted enough for the flight to take place.
The B-17 was escorted by a helicopter - I heard this was required for either communication or navigation requirements. I don't recall exactly.
We were told that there would be no "review" pass permitted. However, some kind of "problem" was discovered, resulting in a go-around. I think the problem was the pilot had a serious eye ailment. (He couldn't see a reason to not do it.

)
Here's a pic of that pass:
Here's a shot of it approaching the parking stand:
That day was the first time I ever saw a B-17 fly and I will NEVER forget it.
From what I was told, this was the first flight the aircraft made since the completion of the restoration at the Renton facility.
g.