You guys are thinking about this "sight" concept in a much too limited perspective. Possibly the Aliens could get information on layouts of the area from their host's memories, but I think that is a bit off. You're judging their comprehensions of these sites by a visual memory alone. Aliens have no visible eyes (just the eye sockets within the skull). They could be using all kinds of different body systems to "see" the layout of the area. Scents, Echoic signals, mental communication signals, w/e. I believe there is far more than simply sight to how these magnificent beasts understand their surroundings. And I know they have at least some kind of mental communication frequency, due to the fact that the Queen can communicate with them, and not have to scream anything (as seen in Aliens). There is far too much complexity to their body structure, to limit them to only one kind of "sight".
