Being in a foreign place, preferably for the first time, having seen many things and collected new impressions, and returning to an empty hotel room with an hour or so to blow. That mix often yields fine results.
If someone gave me the chance to create something, I put myself into it. I just want to try to do something that will last forever and that won't leave people saying, 'Gee, it could have been better, it could've been this, it could've been that.