A full-fare F ticket DOES give you admission to the very nice National Club in Las Vegas. You can expect a nice snack no matter what the time of day. In the morning, they usually serve hot breakfast breads. Midday you might get a bruschetta, and in the evening a cheese plate.
Preflight drinks are usually served in glasses. Sometimes there are hot towels. It's by far the best short-hop F service in America that I have experienced.