When searching for an image, there are 2 steps:

1. What sort of image works best?
2. What actual image is the best (and can I use without copyright issues)?

Recently, I needed a panorama overview of a retail store. Most stores do not have 20 meter high ceilings (a waste of space, a waste of energy), and stock image sites only provide images of actual stores under an editorial license (news papers can use them, marketing presentations not).

A broad Google search brought me to the Galeries Lafayette in Paris (step 1), after which it was easy to find a nice, high-res, creative commons image (step 2).