from my observations:
There is always only one bartender, so no point making nightclubs with multi-store bars. People should know this by now yet new ones keep being added to the gallery...
Same with DJ's. Don't put an extra DJ booth in unless it's in a sealed off club area. There's always only one DJ.
There's also always only one gym trainer, yoga teacher and restaurant greeter.
There is never more than two massage therapists, foot / hand therapists, waiters or chefs. No matter how many stations you put in.