Global Entry is fabulous
I just wanted to put in my plug for how fabulous GE is. I signed up at the beginning of this year and I've gotten to use it several times. It can be a HUGE time-saver -- especially in places like IAD where the customs lines are impossible. I think I've already saved several hours of line-standing time.
My one piece of guidance: say 'No' to all of the questions on the customs declaration if you can possible manage/rationalize it. On a recent entry I marked 'yes' for 'Do you have any food' because I'd bought some cheese in CDG DF. That forced me to get back in the regular line to speak to a real, live customs agent.