Too long ... too short ... just right?

So I was wondering if perhaps I make my tales too long. I've always heard the axiom that a story should be only as long as it needs to be, but I find myself incapable of weaving chapters of less than 4,000 words. Sometimes I'll be done with a chapter of my story and realize that I've managed to throw almost 9,000 words at it. Then I go through and cut what I think is unnecessary. However, it still ends up being a lengthy piece.

I want to keep people entertained with vivid imagery and description, but I don't the audience to get bored with all the prose.

Is less really more?

Samantha