If you're looking to mix materials, get the help of qualified kitchen designer in order to get it right. IMO you should stick with the walnut for uppers and lowers and go contemporary with the door style. Unless you want to redo in five years.

I would not do walnut with the floor you have if you want a contemporary kitchen and what is it you don't like about white?

we've just seen too many white kitchens in the last while and have grown really tired of them. also looking to have a warmer overall effect - the clean lines of contemporary without the starkness