Any kind of sci-fi is a lot of different types of architecture. Just choose one that you'd like to do and stick to it. Maybe choose a movie visual that you like and see if you can recreate it.
This is looking real good Sam... They all look great but if I had to choose I would say I like the bottom right... Whichever you choose will end up turning out sweet!
Not many people choose to finger paint, don't know why people would choose to do so in PS. :P Looks interesting though, looks like it'd have some pretty interesting uses.
Let say, you really like doing product modeling and visualization then modeling game assets but the problem is there is only 1 company that does product viz and 5 companies that make games. So which path will you choose and why?