Old… I’ve lived frugal, and feel semi retired. Having long associated with and contributed to civic, hobby or political organizations, it’s apparent most are made up of retired folks. Thus, they’ve become my friends, many still far older than myself. Other than making me ‘feel young’ by comparison, it’s sad to see the direction we’re all headed..

Non existent!

Interesting to think about. Would start with my wife, Sweetie, who is also an atheist. My wife and I play in a Celtic band, and some have been playing together for 15 years. Have a group of older guys that do property maintenance at our church every Thursday morning. Enjoy working and talking with them, and we have a good coffee break. When I was working full time as an engineer, had a group that went to coffee together. Since retired we get together for lunch. Still friends with a couple of Army buddies. And one high school friend. Belong to a humanist group and consider most of them friends. Have a large family, and am friends with several of my kids (now in their 40's and 50's.
Patterns - The later ones are mostly skeptics, free thinkers, analytic.
Close friends - a journalist, school teacher, Vietnam vet truck driver; engineer; insurance adjuster; another school teacher.

Um ... a circle?

None at all-they are all so different-2 girlfriends that I'm still close to and they haven't met each other though they friended each other on Facebook.

I live in a rather white region, but my best friend is Asian and I have black and Arab friends as well. My second best friend is a woman; we've known each other since high school. Many of my friends are nonreligious, though most probably aren't atheists (but religion doesn't often come up), though some are Christians (even fundamentalist) and Muslim. I should point out that I don't have many close friends; I'd say I have four or five good friends that I'd feel comfortable asking a personal favor of, and the rest are friendly acquaintances and co-workers.

As for professional background, one's a law student currently (former journalist, former speechwriter). Another is a dance instructor. One works in politics, but used to be in journalism. One's a dentist. Another is retired. Another is a mechanic. Massage therapist. Teacher. That exhausts my closest friends lists. Among the rest, it can be anything from custodians to directors of nonprofit organizations, artists to IT professionals, journalists to priests.

So, I don't know about themes or patterns. It's pretty diverse overall, other than being significantly Caucasian because of where I live. But in terms of socioeconomic background, age, education, etc., there's quite a lot of variation.