Your casino heirarchy is correct, except for your separation of regular poker players & low limits.

As a restaurant owner, those 8 guys ordering filets (playing $30-60) and the guy ordering the cup of coffee ($2-4) both make the same amount of money for the casino ($4/hand rake). While a little more clueless, the cup of coffee guys are usually more friendly and tip better. And there's a lot more of coffee cup drinkers.