I would call them cocktail parties on steroids, maybe. As far as we understand, the level of conversation at a salon was extremely elevated, with witty comments and bon mots, hidden meanings, interesting comments and allusions to this and that, and astute observations, constantly. Whereas a cocktail party today is a lot of boring stuff like "What do you do for a living," because this is how we tend to speak now. The way conversations were held then has more or less died out. There is a lot of interest in this kind of discourse in recent scholarship, falling under the umbrella term of "sociability."

I have read that in certain elite salons, the guests had to earn their keep by being interesting enough to hold their own in a conversation.

Different salons had different guests and different focuses. There were aristocratic salons, of course, but there were also artists' and intellectual salons. The goals and the happenings at these would be different. A musician may play at an aristocratic salon, but their presence might be more like a servant rather than at an artist's salon, where the same musician might be a treasured equal guest (or even the star of the party) and play for a musically sophisticated audience who actually cares what they are doing.

You must also remember that genders did not typically mingle in public, so the salon was a place to talk to people of the opposite sex. So it was a "private" party with different, less rigid rules, which makes things fun.

Being satisfied after a salon gathering would have to do with your personal interests, but also the quality of the guests and conversation. You would want to have met interesting (and powerful) people, had stimulating conversations, maybe achieved some social climbing or career-boosting, and feel like you were at a truly special event.

I am not aware of any salon program, but there may have been planned activities or events, depending on who was present (so and so will read their poetry, so and so will sing).

Sources: Stephen Kale, French Salons: High Society and Political Sociability from the Old Regime to the Revolution of 1848 (Johns Hopkins, 2005).

Antoine Lilti, The World of the Salons: Sociability and Worldliness in Eighteenth-century Paris (Oxford, 2015).

Dena Goodman's work.

An interesting primary source (if you read French) might be the Duchesse Laure d'Abrantès, Histoire des Salons de Paris.