There were hundreds of stage coach companies; I'm sure you would find some records still in existence, while others are gone, and still other companies kept none. The easiest way to get this sort of information, however, would be the local newspapers: they frequently published arrivals and departures by stage. Tracking down people who were expected to arrive was a difficult thing. There are many accounts of people traveling to attempt to find relatives or friends who seemed to have disappeared. Mary McNair Mathews, for example, came West in 1869 to track down her brother - or at least his estate - and then she wrote a narrative of her experience: Ten Years in Nevada.