I'm going to talk about families, though, too, and who was established as having what family. Dialect, too, because that speaks to social class. All the ND students except for Rory speak American Standard English. That's an American TV convention, except that on TV, some minority characters speak in other dialects or speak with accents. There are more wealthy characters than poor characters on American TV, and sometimes poor characters have dialects that make it evident that they're poor. But all the glee club students except Rory seem to have American Standard English as a first dialect.
I'll start with the graduates. Mike is established as having a father and mother, and his father apparently works at a white-collar job. Quinn was raised with two parents and a sister, and her parents lived in a nice house. Mercedes has a father who's a professional (dentist? doctor?), and their house has a spare bedroom. Santana's father is a professional, too, a doctor, I think. Her mother saved up a lot of money for Santana. Santana's grandmother has an accent, but speaks fluent English peppered with Spanish, and has a nice house. Santana talks about Lima Heights Adjacent, but her family seems to be well off. Also, she speaks African-American Vernacular English from time to time, but it's clearly not her first dialect. Santana sends some mixed messages about social class and race by what she says sometimes, but the dominant message for social class is that she's middle class. Santana has stated, "I'm Hispanic," so that's her word on her ethnicity.
Puck is established as having a "deadbeat dad," and lives with his mother and sister. Puck has a pool-cleaning job, and seems to do relatively well with that, so he can buy his own things. However, it's likely his family is poor. Finn starts out with a single mother who's poor, and Finn doesn't have a job in the first few episodes of the show, though he gets a couple later, one because he's pretending to be disabled, which is horrible, especially considering the statistics about disability and employment. Puck and Finn both speak middle-class American Standard English, though, which is an advantage in getting jobs.
Rachel has two parents and a nice house. Though she wears dreadfully unfashionable clothes, they're not cheap clothes. She and her parents speak American Standard English.
Burt owns his own business. He's blue collar, but well off. Kurt has a ridiculous budget for clothes, though that's the show. Oh, and the Hummels can afford to buy saffron in a town that it's hard to find it in. It's a little detail, but it still speaks of money. Kurt is notably articulate, and his English is more upper-middle-class American Standard English. This is really an advantage for getting employment.
School is something else. Sam started out in a private school, then went to public school -- McKinley -- and then his father lost his job, so Sam went from relative wealth to poverty. Sam got jobs to help with his family's finances. Still, Sam's English is middle-class. Sam is established as having two parents and two siblings. Blaine started out in presumably a public school, but his family could afford to send him to a private school with a "steep" tuition. Blaine's English and manners are at least upper-middle-class. Blaine is so far established as having a father and a brother. His brother does well financially, or so it appears. Actually, all of the Dalton students we've heard speak speak American Standard English, and seem to be upper class. Blaine's family also has the money for Blaine to be able to afford good clothes.
Tina, once she stopped faking a stutter, speaks American Standard English, and can afford relatively expensive clothes. Artie, though his clothes are unfashionable, has nice clothes. He's established as having two parents and his family has an adapted vehicle for transportation. Wheelchair-adapted vans are expensive. It may be seen as a necessity for him, but his family had the money for that. Like Kurt, he's very articulate and speaks upper-middle-class English. (Added: Artie easily code-switches between American Standard English and African-American Vernacular English, so he knows AAVE as well as or better than I do. American Standard English is still his first dialect.)
We don't know much about Joe yet, except that his father is a Bible salesman and that Joe speaks American Standard English. He was homeschooled, so his mother stayed home with him a good part of the time. Sugar is wealthy. Rory's family can afford to send him to the U.S. as an exchange student, but can't afford plane tickets for travel to or from Europe for the holidays. Brittany has a nice house, or at least a nice room, with a house that has a spare room and a family that can afford to travel. Whatever her breaks from consensual reality are, or whether she has an intellectual disability, she speaks American Standard English fluently.
Because I can, and she might transfer schools, Wade "Unique" Adams has nice clothes and speaks American Standard English.
So Finn and Puck are from poor families. Families headed by a single mother are more likely to be in poverty than families with two parents, or so I think the statistics are. However, them speaking American Standard English as a first dialect is an advantage for employment, as is them being white and male. Finn has now joined the Army, and the military is its own kind of thing when it comes to employment. We don't know where Puck will go after the third season, but he has a high school diploma.
So far as has been established, Kurt's the one who appears to be from a higher social class than his family actually is, but his family has money. Kurt not passing as straight could well be a disadvantage when it comes to some kinds of employment. Unique being transgendered could be a terrible disadvantage when it comes to employment, though she could pass as cis-male if she wanted to. Well, unless the Employment Non-Discrimination Act passes someday, but there would still be discrimination.
I didn't find it hard to talk about social class for the characters. When we've seen their houses, we can go by what their houses are like. We can see their clothes and hear their dialects. We can think about whether they're likely to face job discrimination, and if we've heard about their families, judge what their family's likely income is. Most of the students are of at least middle-class social class, or sound like it. Some look and sound upper class. There are various things about passing and not passing that I didn't get into except for sexual orientation and gender identity. But still, their dialects and clothes say a lot about whether their families have money, or appear to, in Sam's case. His family had money. Sam found it easy enough to get employed.
Make of it what you will, my overseas readers.