First off: orange hair fiasco from two weeks ago has mostly resolved itself, without any extra visits to the stylist. I washed it a lot and it quickly faded to an acceptable warm blond, although when I see the new stylist next month I'll get her to tweak the colour a bit. But the key point is that I no longer look like I'm trying and failing to be a redhead.
One thing I'm noticing is that with substantially lighter hair, I look both younger and healthier. This is interesting because I have never been a natural blond. (In early childhood it was a very light brown and it darkened to medium/light brown by adulthood). I used to think that nature gives you what you should have. Now I'm not so sure! I used to colour my hair blond in my twenties, and always liked how it looked, but I never though it was more flattering to my face than brown. Now that my face is showing signs of aging, I am surprised to see that the blond is actually better than brown.
I wonder if this would also be true if I had a lot of grey. At the moment I don't -- just a sprinkle at the temples, really -- but I wonder if it was 50% white, if it would have the same effect. There are a number of women on this forum (e.g. Suz, Una) who are doing the grey and it looks phenomenal. Does lighter = better as we move past, oh, say 40?
(The other thing I've noticed is that my dark brunette friends who have a LOT of grey are no longer having great results dyeing over it. The grey hairs seem to absorb brown dye funny, so the whole mane ends up looking dull and wiry).