Iciban - I didn't use zBrush on the first few assets including the teleporter, but I did on my current one, though I overdid it. For the low poly I save out the mesh before I add control edges and small details so I can go back to it later and optimize that rather than my finished high poly. However, this does require me to rebuild parts from time to time. As far as baking goes, it's just a lot of trial and error. I explode everything and do test bakes to find out where I should put hard edges and UV seams and try again. In the end I normally end up putting a couple maps together in photoshop.
danjohncox - Bah, I was hoping for some better news. I'll have to play around with my lightmap UVs and the packing to try and get the best I can out of it. Thanks for the info.
Tiny update for now, just started work on painting details, still no spec. I don't know if I'm just kidding myself with that hex pattern or not.