To possibly throw some extra work at you guys, in a recent game that I've been playing the spice worker unit automation seems screwy. Sometimes it works o.k., but a lot of times, the workers will walk straight to cities and stay there, even when there is open spice in my territory. I am not sure whether this has to do with distance, or some other factor (The spice workers seem to handle automation better when they are already on spice, though this is by no means certain, and the distance to the open spice doesn't seem to matter as much.)
I have read about some AI spice harvester issues earlier in the thread, so am not sure whether these two problems are related (These are my spice workers that are screwy, just to make things clear).