My own time-lapse experience.
 

Figured I might as well join the fad.

http://www.youtube.com/watch?v=cspzwt5rXfU

Enjoy. This was all done by hand mind you. Just a tripod, me, and my camera. No remote, no timers. Legit. :D

I'm curious as to what settings you have the camera set to in order to get the sun set photographed and then switch to the night time photographs?

Did you just have the shutter speed increase as it became darker?