There are other middle-class natures that seep into our writing. Education - everyone goes to college and is trained in something that becomes their life work. Many choose jobs they hate, change them over and over or wander through life unable to decide. The 9 to 5 world we live in isn't always 9 to 5. Many have a passion that they explore in the wee hours left us between family and work.
Characters are passionate people who live unique lives.
Middle-class fashion, there are clothes beyond jeans and the drab suit and tie. Look at fashion shows and awards, travel videos and documentaries for ideas. Educate yourself in what people wore long ago and will wear in the future. Think beyond your closet. Language is big and is usually very telling of a person's background.