I think all of the answers here are right. There really isn't a wrong answer for this question. Like R@nSiD said, it's really up to the individual.
If you're trying to keep your geometry numbers down, then only bevel objects that are the main objects in the scene, and that are easily visible.
If you don't really care about how much geometry you have created, then I'd say bevel everything, within reason, just in case you may want to showcase an object later on in a different render, that wasn't necessarily visible in this shot.
If it were my choice, I think I would go ahead and set that high level of detail on everything, if it didn't take too long. I realize that this scene has a set camera, but who knows. Maybe you'll use it for something else, and want that nice detail later on.
Just a thought.