"My question is this, where do you personally meter?"
Depends what I want.
At the scene when I am setting up, I think:
1. latitude of the film /sensor
2. main element of scene
3a. Do I want to post produce – slightly blow the highlights and recover them later
3b. Do I want to post produce - multiple exposures and then layer
In the top image (sunset) I used exactly as you, the water reflection – I wanted the black foreground to form a frame. There was no post production except sharpening – it is the JPEG out of the box 20D / Kit Lens, about F8 I think.
In the middle image (sunrise) the Green was important to me, so I metered the bush and then taking into consideration the Exposure Latitude of my 5D, underexposed that value slightly – that meant the highlights were still blown, but I recovered what I needed (though not all available) in Post Production – and I still could bring enough green out – so I took this one with the aim to Post Produce it.
The bottom image (Early Morning, storm brewing) is also the JPEG, straight out of the box (5D) – I just wanted the colours of the sky. I metered on the blue sky. I think I would have underexposed from that reading maybe ½ stop or so.
I rarely use filters for this stuff (now I am with digital) – even though I have a box of them.
I find the challenge of going naked, more fun, and I have that strange passion to just nail JPEG images.
***
"i have no idea why the grad filter produced a deep red sky, it did not look this way from memory"
I assume it was a Graduated Neutral Density filter? – likely because your eye was looking into the sunrise your brain was doing a lot of compensation, hence you did not “see the red” – the GradND Filter had maximum effect over the sky – most likely just underexposing it.
Also the other key to the depth of “Redness”, will be in the Colour Temperature you set, or your camera set for you.
WW