I have been asked to create a search that will provide the most costly searches that are run. I know from reading other posts that I can get this from the SOS app. But I haven't found the search that provides this information. I also need to add it to a dashboard.
It really depends what you consider to be an "expensive" search!
Is a search that uses several gigabytes of physical memory expensive? If yes, you might want to check the "Top 20 memory-consuming searches" panel in the "CPU/Memory Resource Usage" view to identify such searches.
Is a search that runs for several hours expensive? If yes, you should probably take a look at the "Search Usage Patterns" view.
Finally, for a higher-level view of your search workload, I would recommend to start with the "Search Activity" view.