[Elvarlyn]

I think a combination of all three levels of dynamic generation is good.

Fully Dynamic:
I know we're generating the vast bulk of our highways and ocean rooms almost completely automatically. We have literally tends of thousands of the latter and no one is going to sit there descing them all, especially given that the only way those descriptions would ever be read would be if your character fell overboard... in the few agonizing moments before it drowned.

Half/Half:
I think this is what you touched on later, regarding including dynamic elements in descriptions. I think we've tended to use this more for mobs than for rooms, but it can definitely spice up both.

None:
The artistic expression others were talking about. Sometimes you really do just want a paragraph of lovingly hand crafted descriptive text to tell people what they see in a given room.