Help! My husband and I are about to renovate our kitchen and I want to know what never goes out of style before we start spending money on this project. What style, in wood type and color never goes out of style?
Hmmm. I hear this question a lot and I'm going to answer it by not answering it. At least not yet. First, let's start by taking a stroll through some kitchen designs of the last 100 years. This is by no means an exhaustive survey of every kitchen style that's come and gone in that time period, but it will help me make my point so bear with me.

Here's a kitchen from 1921.

Here's one from 1931.

Here's 1941

1951

1961

Here's 1971

And 1981

Here's a kitchen from 1991

2001 already looks pretty dated already

And here's what's being billed as a traditional style right now.
As you can see, the words timeless and kitchen don't belong in the same sentence. Even the last photo, the "traditional" one, is pure trend. That layout, those appliances, that cabinetry... it's all very right now. It may take a page from some past styles, but in the era it's invoking (1910-1920), a kitchen looked nothing like that.
Contemporary kitchen design is new, regardless of the style of the room. The idea of a kitchen being the center of activity in a home was unheard of until 30 years ago. Pretend for a moment that it's 1955 and you're talking to your grandmother. Imagine her reaction to the news that you're planning to spend the equivalent of half your annual income on a kitchen renovation that will become the focal point of your home. She'd think you'd lost your mind and then she'd tell you to get out of the way so that she could get back to boiling the pot of diapers she'd been working on all morning.
Kitchen designs change because our culture changes, and it's not just a function of trends in taste. Social changes, technological changes, economic changes, etc., evolve and reinforce each other over time. You'd hate an authentically period kitchen because you don't live the way people lived 20, 30, 40 or 50 years ago. How things look is inextricably linked to how things work.
I say that there's no real answer to your question. Renovation and construction always look like the time when they were built or renovated. The minute you start swinging a hammer is the same moment that time stops and how you live right now gets preserved for all time. Or for as long as whatever you're building lasts. So even though I say that there's no answer to your question, here's some advice as you go about deciding how to spend your money.
The first being that quality doesn't go out of style. Well-made cabinetry and appliances that are made to last will get you more years of use and satisfaction than cheap stuff will. In it for the long haul? Stay out of big box stores and get ready to spend some money.
Second, I'd advise you to avoid specialty finishes on your cabinetry. That means anything with a glaze, a distressed paint or anything intended to give new cabinetry or furniture instant character. Character has to be earned and that's as true of your cabinetry and furniture as it is about your personality. Short cuts to character don't work.
Third, avoid adding colors that are right now to things you can't change easily. A good case in point is the light blue and brown color palettes that are still all over the place. Getting light blue appliances, a finish color available from Dacor right now, might look good for now but five years from now you will hate them. If you love that blue and brown palette, get blue and brown throw rugs, not appliances. A blue throw rug costs $20 a blue fridge $3000 to $4000. You tell me, which would you rather replace in a couple of years? So the lesson here is to accessorize with trendy colors, don't build them in.
Finally, do some research on where kitchen design has been and where the experts think it's headed. You cannot anticipate what's next with any degree of certainty, but you can take steps from getting yourself locked in the past too tightly. The idea that the kitchen is the center of a home in 2009 is not something that's going away any time soon. But this Old World style that can't go away fast enough is a recipe for heartache later. Where to turn for guidance you ask? Hire a professional kitchen designer to help you realize your dream. Explain very clearly to him or her what you want to do and have this designer be standing in your home while you do this explaining. Think this through and have a detailed plan before you start writing checks and you'll be a lot happier in 10 years than you would be otherwise. Whatever you end up with, be sure that it reflects your life, your hopes, your needs and your wants.