Just the other day, I was looking through some shots from a trip my wife and I took to Italy.  It was our honeymoon, actually, and it was many years ago.  I was still using a relatively simple point-and-shoot Kodak camera at the time, but it took quality pictures.  (Yes, there was a time when Kodak was a common name in cameras.  It was a long time ago, on a vacation far, far away.)
In this case, we were visiting a small town in Tuscany, and I lined up a good shot of a small "street" (for lack of a better term). 
I got two shots, one of an empty street:
...and one of the same street, but with my lovely wife in the foreground:
The sky is blown out in both shots.  As I said, I was just using my point-and-shoot, and it was the middle of the day - but I think it's OK, because your eye is drawn to the street scene anyway, and the gray sky sort of corresponds with the gray street surface, and keeps with the overall color theme of the shot.  (How's that for a justification for a blown-out sky?)

Anyway, I thought this was an interesting pair of photos, because it's clear when looking at these two images that a point of interest, my wife in this case, is desperately needed in the shot.  Your eye is immediately drawn to her, and then to the rest of the street scene.
The photo without my wife is simply not as interesting, or well-composed.  It's a nice shot of an Italian street, but it's just missing something.
Of course, in my opinion, my wife makes any picture better.
Comments or questions?
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Thank you!