Not knowing what the style of your house is, it's really hard to make a recommendation. However, a good friend installed large format, rectangular, slate-look porcelain tiles in her home and they look really good. Slate has been around forever and in my mind fits the "timeless" requisite. Hers looked very similar to this one:

Thanks torreykm! Our house is tradional but I like a farmhouse look. I like the slate look myself but just don't want greenish blue tones. I'm pretty sure I don't want real dark tile but something that will look good with my stained cabinets.

A few more options.....

Oh I really like the second one! And I've always loved brick flooring, but that's probably out of our budget.

I like the first of the stack of three that Torrey posted for a mudroom. Just be sure that it will be easy to clean!

And Torrey - I love that Daltile slate! In fact, I love it so much that I'm going to seriously consider it for our tiny front hall. Thank you for posting it!