I have a number of projects taking up much of my time, and a lot of procrastination eating away at the rest. So, I think I'll just ask some questions. Feel free to answer, or don't, or talk about something that interests you right now.
Some setting materials are designed with a particular game system in mind, so that the magic system fits the physical structures in the game world (Hârn does this, where the places the magicians live are built around the Hârnic magic system; most games do the same for religious structures, of course). When you are using a product with a game other than the one it was designed in conjunction with, how do you handle that? If your game of choice has a magic system that centers on massive fireballs and lightning storms as the magicians' combat abilities, how do you fit that into a low-magic setting's products? Or whatever.
In general, how do you use setting products? Do you always take the setting and run it as it is written? Or do you modify it to suit your tastes? Or do you even just pull out small sections, or even single locations, and set them down in a setting of your own design (that's my general use, though some settings, like Oerth, are too good to break up like that)?
When you are designing your own setting, do you use the assumptions in your game of choice directly (encounter tables, price charts, etc)? Or do you carefully redesign those components of the game to better suit your vision?
What is your general process for designing a setting? Do you have ideas that you set down before even sitting down at the table with the players? Do you have some general ideas, but keep things loose so that ideas can come up in play? Do you just let it go and do all of your designing at the table? Some combination of these?