In the thermodynamics case Chandler's stat mech book spends a good amount of time on these as applied to things like fluids: given that a particle is here, what's the particle density x cm away? The fluctuations for atomic-size distances tell you about packing structures and similar microstructural features. Imagine having a collection of circles packed together on the plane, and asking "what percentage of the points 1 um away from me are intersecting a circle?". This will eventually wash out to the overall packing density, but over small distances it can tell you more detailed information.
also Chandler and Hill which are pretty cheap
https://www.amazon.com/Introduction-Modern-Statistical-Mechanics-Chandler/dp/0195042778
When I first took the class, we used: http://www.amazon.com/Introduction-Modern-Statistical-Mechanics-Chandler/dp/0195042778 I needed more of an than this provided, but I like the style. The next time I took it we started with: http://www.amazon.com/Fundamentals-Statistical-Thermal-Physics-Frederick/dp/1577666127/ Which does a good job with introductions, examples and practice problems and there are solutions online. We then worked a bit in the Chandler book above. This was good, but the book I've found most helpful has been: http://www.amazon.com/Statistical-Mechanics-Donald-Allan-McQuarrie/dp/1891389157 which I use for reference now. Edit: Explanation