Dark Walnut over Oak is a great combination.

red oak or white oak please?

This is red oak.

What finish did you use on the floors? Satin or matte? thanks

Satin

It's beautiful. We mimiced our floors to look just like this!

on another version of this picture, it says that this is white oak - can anyone confirm if its red or white?

No, I am fairly certain this is red oak. Also, if you are staining this dark, it doesn't really matter - i.e. go with what is cheaper at the time of purchase of flooring. It becomes a much bigger issue when you are staining LIGHT. If you are trying to go light and you are staining on red oak it can tend to look pink. In that case, i encourage you to make sure you use white oak.

Thanks! We have red oak floors, trying to make sure we do the right stain. Is this water or oil based? or, rather, what would you recommend?

Have your floor guy test relatively large swatches of different stains on the actual floor before selecting the color so that you see how your floors. Water-based dries faster and has less odor (which some people with kids prefer). They claim water-based is just as durable as oil-based but I feel that oil-based is slightly more resistant to surface scratches.

many thanks!! i appreciate all your help!!