Frank, instead of turning off all those various services, you might want to try this one: Settings > General > Network > Cellular Data Off. Especially if you’re going to be on wifi for a while, so you’re sure no cell data is sneaking through somehow.
It is a drastic solution, but I think this next month I am going to keep Cell Data turned off as a default, turning it on only for specific instances when I want to use the Internet and then turning it off again afterward. I will be very interested to see if my data usage continues to be unnaturally high (I spent 20 days of my first month with the 4S like that after I blew through most of my 200MB in less than a week, but I have been slowly leaving it on more, and my data has been climbing back up as a result. Like many of you, I had similar usage habits on my previous phone (iPhone 3), but my data usage only ranged from 80-140MB per month.
The AT&T rep claims he doesn’t know anything about increased data usage problems with the 4S, and suggests that it might just be 4G that is responsible for the increased data usage. We’ll see, I suppose.