I read, and really like, this description of food and classes:
- Lower class: was it enough food?
- Middle class: did the food taste good?
- Upper class: was the food interesting?
Nice restaurants in SF are somewhere between #2 and #3; the more you pay, the more it's at #3. Small portions are expected.
The reason for this is because you can saturate #1 and #2 by reaching a level where people aren't willing to pay more to get more. #3 can't be saturated.
There's an upper limit to how much the human stomach can hold. All-you-can-eat buffets serving cheap, starchy, greasy food optimize their price point to what the market will bear. Past a certain point, charging more per plate is a money-loser because customers balk at paying more than that specific price for a meal when what they're buying is quantity. Fast food dining generally requires about an hour's take-home pay. Ask more than that for food that is simply edible and not pleasant, and people start balking.
Satisfying the sensory expectations of the diner is easy: just load up the salt, sugar, and grease, and add a few unique seasonings. That's how volume dining works. For volume dining, you can ask about three times the average hourly take-home pay in the region, and do good business. When you start asking more for things that are tasty, significant numbers of people (middle-class and otherwise) decide to get their gustatory pampering elsewhere.
You can't max out "interesting" or "pleasant experience", though, because of hedonic adaptation. No matter how luxurious the surroundings are, people get used to them, and they don't feel like they're getting something unique anymore. Charge $50 for a glass of wine and $500 for a martini, and there will always be someone else who manufactures a reason to charge double the price. At that point it's not what kind of meal you deliver but how you deliver it. Load up on the pretentiousness, so that you've got French accents among the table waiters, Italian marble in the crapper, and unique, custom artwork on the wall. Create some kind of buzz by wrapping diners in tablecloths or doing some other randomly stupid thing. Then you can charge as much as you like, and people with more money than sense will start buying exclusivity, service, and ambience.