For a random non-operational log analysis that @Ironholds and I needed to do, we wanted to query for requests that were cache misses in (all of) esams and needed to be requested internally back from the eqiad origins. The "hit/miss" field by itself doesn't say anything for this, as these are Varnish *frontend* misses, which in turn can be either hits or misses in the esams backends.
Furthermore, as we scale up to another primary DC (codfw) and more caching PoPs, increasing the number of paths a request can take to be ultimately be served (in both Varnishes & appservers), it might be useful to record the whole path that a response took within our infrastructure, as recorded in the X-Cache header. This would be especially useful for erroneous requests (5xx etc.) but generally useful even for the generic webrequests and non-operational queries, such as the one we initially tried to run for this analysis.