Category set up for multi locations

My first few CPT’s I created a lead category, then sub categories. I would like to know if I need a Parent, to have the sub categories..see Places, Specialized Diving, Events. Or no parent necessary. Because each category asks you if Parent, I first thought I need to make that CPT the parent of the categories.

-please provide link to support on setting up categories and SEARCH mechanisms built in and what the logic is to find something, so I can build these pages with better precision.
Thank you.