A few years ago Thom and I did a night time century on the tandem. It started somewhere in Davis, went out to a highway overpass and turned around. It was dark and I was on the back of the tandem so I don't know exactly where we went.

It was put on by a club though, I think. The cost was like $10 a person and they had Subway sandwiches, sodas and coffee at the turnaround point.
I do know it was all roads and it was all flat. We started about an hour before sundown I think.
Veronica