I like to do data-oriented programming, and was just thinking about how I want to organize (and search through) the primary data structures/concepts for a project I'm working on. Part of that involved thinking about things like what information I might cache and what representations data might take. That lead me to looking into the nuances of things like B-Trees, AVL Trees, Quadtrees, k-d trees and so forth.

I've found the book "Foundations of Multidimensional and Metric Data Structures" by Hanan Samet to be an excellent resource when looking for a slightly deeper dive than a more introductory algorithms course. It goes in depth on the nuances of these approaches, many of which are highly similar at a cursory glance.