I wouldn't mind seeing an area of the ship/station completely overrun by wildlife so that man-made and organic elements are perfectly meshed together into a new environment. I know Metroid has done similar things before with areas like the Chozo Ruins from Prime and such, but I mean REALLY overrun by nature to the point where you can barely recognize what was constructed there in the first place. It would allow for some interesting mechanics in my mind, like having a bunch of vines wrapped around some object which could be hiding something behind them. A rainforest type of setting would be cool too. Lots and lots of plantlife and tons of variety in both the environment and its inhabitants. So basically something that's full of life and very dangerous at the same time is kinda what I'm looking for I guess based on those two suggestions. Think Brinstar kicked up a notch.
Your Mainbar: