When I talk with new and prospective clients, one of the first questions I ask is about website function. "What do you want your website to do?", is what I ask and then I listen closely to the response.
What I listen for is a response that describes function rather than look and feel. My experiences have shown me that most people focus on what they want the website to look like, but put very little thought into what the website is to do.
Website function should be your primary focus. You should know what you want your website to do before you even start talking with a web designer or web developer.