For instance, I am at a very large, midwestern state U right now, and it seems like 25-50% of the students I teach have spent a year or two in community college, and perhaps even have an Associate's and some work experience. Many of them are local, some not; they work hard, and a good amount of them seem to get their bachelor's degrees in their mid-late 20s.
I obtained both my undergraduate and graduate degrees at midwestern universities, and I currently teach at a midwestern CC. I would have to agree with the above statement. While I earned my BA at 22 and MA at 24, I did attend a CC for the first 2 years and most people I know did as well.
The CC that I work at now is very large, we have many students who are using it as a springboard to a 4-year university. We also have many adult students. It is a really diverse campus consisting of all racial and ethnic groups, with students ranging from 16 to well into their 70s.
When I was working on my BA there were many students studying with me who were 25+. Although I think the average age will vary based on the school. From my experience, universities that are typically considered commuter colleges for the locals have an older student population. Large state schools and SLACs that attract students from throughout the country, seem to have a younger student population.
I'm not sure how working environments vary from region to region (as I have been in the same region my entire life), but I do think that the college itself would have more of an impact on one's working environment than the actual region it's located in (unless it's in the middle of nowhere, in a poor area, or in an area with a high cost of living).
This being said, the area that I live and work in has lost a lot of jobs over the past year or so. Due to this, it seems that there is a larger number of adults taking classes to either update their skillset or make the transition to a new career.