So, this question is more for the world builders out there...
Where do you get your ideas for the worlds you build?
How do you choose the designs and layouts of what you do? Do you just place objects according to aesthetic values, or do you take flow and pacing into account?
How much pre-planning do you do before you begin building? Do you do any concept work?
Level design has always been my favorite part of the game development process, and I'm just interested to hear some tips, tricks, techniques, and advice from some other people who have been doing the same thing for awhile.