I'm watching "For a Few Dollars More," and Lee Van Cleef steps into the saloon, and darned if it isn't the same setup as every saloon in every Western T.V. show and movie:
Bar on the right (or sometimes to the back)
Upright piano on the left
Staircase on the left of the back wall, leading up to a second floor with either inn rooms or a brothel.
Is this a faithful recreation of an old West watering hole? Or just Hollywood reusing its sets?
Even the recent "Once Upon a Time in Hollywood" uses the same layout for its Western scenes -- though I think this is intentional -- an homage to old Western sets.
I've read a bit on it but will defer to some great answers already posted here by one more learned in the ways of the Old West. According to [this] (https://www.reddit.com/r/AskHistorians/comments/gpp4at/did_saloons_in_the_old_west_have_doors_besides/) recent post by u/itsallfolklore as well as other sources, no. They were short on the street side and long on the "alley" or non-street side, so they wouldn't have that large square "great room" immediately after entering. This certainly would impact using the "Hollywood layout" as a standard. The bar would typically be on the side since that was the longest wall, but that is about the only thing Hollywood did get accurate.
Another thing that Hollywood gives us is a different orientation: doors open in films on the longest wall. Saloons, in fact, were orientated to have the least front footage since that was the expensive real estate, so doors opened to long narrow saloons with the saloon leading back to the back wall. But that doesn't work for cinema, so Hollywood turned the saloon so the doors opened to the broad bar on the opposite wall. Batwing doors were used occasionally in the Southwest, but they were always backed up with tall doors that could seal the saloon for security or against the wind (and occasionally cold winter nights).
Another [answer] (https://www.reddit.com/r/AskHistorians/comments/86qwhp/what_kind_of_music_would_have_been_played_in/) by u/itsallfolklore deals with music in Virginia City. Not all saloons had pianos. It is likely of those that did not all would employee piano players. Some patrons would bring instruments, play bar intsruments, or sing while in the saloon, and just like bars today they catered to different demographics, too. This would influence what, if any, music would be found there.
Thanks to /u/Takeoffdpantsnjaket for the links.
To provide context that affected architecture and other choices: the West is the largest region in North America; it is extraordinarily diverse, and so whatever generalizations one attempts to make, there will be exceptions. Hollywood (and the Italian "spaghetti Westerns"), however, tended to focus on a specific type of West that tended to be post-Civil War/pre-turn of the century, and that was part of the semi-arid West of the high plateaus, a region that was dominated by mining and free-range cattle.
Towns of this Intermountain West tended to exhibit tightly clustered architecture - something that is not normally part of the expanded "Wild West" town of film. One of the simple facts about the West is that most people did not own a horse (contrary to the way the place is depicted). That meant that most people walked wherever they wanted to go in town - shopping, church, visiting friends, and work. To have a town fit this pedestrian model, structures were normally built "wall-to-wall" and frontage footage was the premium when it came to real estate.
These factors combined to make the typical saloon long and narrow, with the entrance opening to a long bar that projected nearly - but not all the way - to the back. There was usually at least 18 feet (5.5 m) of frontage which allowed for the backbar (a cabinet for storing things); room for the saloonkeeper to walk up and down the bar; the front bar (which included a foot rail so patrons could stand with one foot raised as a matter of relaxation and comfort); and finally, enough room for patrons at the bar and others to walk up and down alongside the patrons at the bar. Generally there was an open space at the rear of the large room - where the bar ended. This place could accommodate a table or two or a pool table (if it was a billiards saloon) or the piano of your question.
Filmmakers no doubt fund this design problematic because camera angles would be awkward and the action of the scene could only be played out in a confined setting. It made much more sense for the "stage" of the saloon to feature the bar as an expanse at the rear of the film set with the players spread our across the camera frame from right to left. This caused the normal saloon to be flipped, with an entrance in the middle of its long axis.