Of course - and as always - the below is IMTU and YMMV:

 

Startowns have unofficial enclaves for each of the major races, including one each for Solomani and Vilani - plus (in my relatively young Third Imperium) Syleans - with a small "neutral ground" neighborhood (the area directly around the starport gate) in between. There would also be enclaves of any minor race(s) with a homeworld within a dozen or so parsecs, usually located some distance from the starport (the higher-income real estate having been claimed by the more powerful races).

 

The starport concourse would be populated in a similar fashion, with any local minor races represented roughly in proportion to how far from their particular homeworld said system was located. If a particular homeworld were to be close enough, members of that minor race could even outnumber the various shades of humaniti on the concourse.

 

Basically, I create a 2d6 table and populate it with races appropriate to that region, then roll for the specific race the PCs encounter.

 

As to the clientele within a given starport/startown bar, that would depend upon the prejudices (or lack thereof) of the operator/regular customers, moderated by traffic density. For Class A ports, bars which advertise on the station cortex (and are actually located on the concourse) have a mixed clientele; use the same encounter table as for the concourse. But there is enough traffic volume to also support bars with a more restricted clientele, usually just outside the port in the startown and along the main corridor/road; use the same table, but the result applies to the entire bar. Class B and C are similar, but with fewer (perhaps even none) restricted-clientele bars.

 

Below Class C, most traffic is going to be human-crewed (it's still basically a humanocentric game after all), though occassional singleton aliens remain possible; use the same encounter table as above, but any non-human result is the *only* alien of that race in the place. If there is only one bar, it will likely be a "general use" bar, particularly if a major shipping line or megacorp has a presence at that port for some reason. But it's far more likely that there will be a bar for each particular *class* - rather than race - of client. But most of the patrons of these bars will actually be (relatively) local; e.g. from elsewhere within that same star system, rather than from out-system. The various bars of Koenig's Rock (at least as I remember them . . . it's been a while . . . ) are a good example of this: one for megacorp (mainly LSP) employees, one for mercenaries, one for transient asteroid miners, one for local "rockrats," etc.

 

And heaven help the PCs when they (inevitably) wander into the "wrong" bar.