Depends on where you live. The Denny's in the Agoura/Thousand Oaks part of metro Los Angeles were always nice upper middle class restaurants when I was there visiting. The Denny's in the southern states on the other hand tended to be much lower scale.
Depends on where you live. Minimum wage workers make ~$30k a year near me. Well north of that if the are tipped since min wage is the same for tipped and untipped workers.
It's funny - in the UK I think we'd say the middle class is getting smaller but the standard is staying the same, while in the US you look at it as the middle class stays the same size but the standard falls. Different approach to social statistics!