This is a great thread .. seems to be a useful topic to learn. I hope you don't mind if I back it up a bit and ask some basic questions so I can keep up:
First, (somewhat embarrassing) question - What exactly is spot metering?
Also, I've used the AE-L button, but apparently did not understand it. I was told thru the grapevine that the button is to 'override' the camera reading. For example, if in TV mode and the camera thinks it knows the F stop, you can point in another direction..half-press the shutter to read the settings .. press AE-L ... point camera back to original subject and shoot. I was told this was good for when pointing into the sun .. turn away from the sun, lock the exposure, then turn back.
It seems like this button has much more to it than I originally thought! I appreciate your input so I can get up to speed.