Laminate flooring

If you can match the color, I'd stick to having the same color throughout.

yeah me too, but I know nothing about style/decorating.

I know on HGTV decorating shows, all the "experts" frown on different color wood floors, and if they don't "flow" into one another (run the same way)

How about the dark in the center and the wide lighter color around the edge?

Can you do a dark/light checkerboard or something creative to tie in both the light and dark woods? I've used a laminate wood flooring in my entryway that came in 12' squares, like floortile.
I like sullyfish's idea too.

Interior design etiquette? There's no such thing. What the designers like this year, will be out of fashion 2 years from now.

You have to live with it for the next 10 years so do what you want to.

I saw a house a few years ago that a contractor lived in. He had used left over hard wood flooring from jobs to do the floors in his house. Each room was a different exotic species. It looked very nice. The required transition strip will act as a divider from one floor to another if you decide to use a different color.

I agree with parados on that - though I might wish the kitchen laminate had been a darker choice (re real colonials, but then they would have had thick hardwood) and then have the whole thing the same. But as it is, I would also probably now make it all the light laminate.

What's under the carpet? What is presently in the living room and hall?

Depending on the house - if it was really old - and the budget, I'd even consider taking the kitchen laminate out if I felt strongly enough about a darker color and had a swell bank account. (I don't.) Or maybe doing all the rest in what I wanted, and weaving at the interface as others have suggested.

On the other hand, if you like the light filled room look, find it fresher, I can see going that way and being quite happy I did.