I look at the astrogator and I think of 2 things. Lost in Space (of course) and Forbidden Planet. When I think ‘Alien Looking’ I think of more organic things. Maybe that’s a prejudice or maybe its the only way I can think of to differentiate them from something that could develop from human technology.
Here are some ships that try to convey alien technology and my thoughts on them:
Farscape Moya: Very organic looking. Asymmetric corridors and doors. Large, flat, uncluttered floors ruin the effect a little.
Farscape Talyn: Moya’s offspring, much less organic and more manufactured.
Next Generation/DS 9 Klingon ships: Cramped, gritty & uncomfortable, but they look manufactured
Romulan & Andorian ships could just as well be future versions of present technology
Battlestar Galactica Cylon Basestar (Modern): Very minimalist but manufactured, even though the show’s characters claim they’re organic.
Stargate Movie & SG-1: They went for an Egyptian/Eric Von Danekin Chariots of the Gods look for this
Stargate Pegasus: I think they tried to make the Egyptian stuff from SG-1 look futuristic. They used a lot of triangles rather than rectangles.
Stargate Pegasus Hive: Back to the organic look.
The Day the Earth Stood Still (Original): Very minimalist, but still could be a futuristic outgrowth of present human technology. When Michael Rennie uses it, it gives a distinct impression of verbal or psychic control.
The Puppeteers (from Larry Niven’s books) are described as having technology that looks ‘melted’ due to their aversion to sharp edges. I think the Z-mech stuff above fits this description.
In the end, I guess it came down to what I thought YOU meant by alien.