Hi Christina,
Thanks for your careful look at these images. Firstly, No 1 is what it's all about for me at the moment which is capturing the light before the sun comes up.
I was at location very close to the above this morning and there certainly was a purple/pink tint in the sky for a period which was more prominent farther from where the sun would rise, I had made a mental note to look for this. But I'm not convinced this was as great as appears in No 1 & 2 above.
You may have also noticed there is a problem with all images, except No 3, in that there's bad vignetting in the upper right corners caused by my Cokin P series filter holder when used on my 18-200 at wider focal lengths causing severe darkening of that area. I seem to recall I have another filter holder somewhere for WA use but if not can always frame wider to allow for this.
The filters I used for these consisted of;
a) Hoya Pro Digital low profile CPL, I believe this gives about 1 1/2 to 2 stops.
b) Cokin P153 Neutral Grey : ND4 - 0.6 this gives 2 stops.
c) Cokin P121 Neutral Grey Graduated : ND8 this gives 4 stops. (for the sky)
This full combination was of little use for blurring water once the sun gets above the horizon when wishing to work between f/11 to f/22. The ND8 graduated seems to work well for the sky in achieving a better balance for exposure, but I would seek advice from those who have far more experience than me.
I am seriously going to consider a vari ND if I can get one shipped here which will give me far greater control for the water.
PS, I actually managed to get a heron shot today, but I do need a longer lens
Grahame