I can echo this. I know a decent number of older folks in the Clarendon/Courthouse area. It’s an interesting mix - because it’s got so many apartments and condos, you don’t see as high a percentage of people with young kids as you do four or five blocks off the main roads and into where there are more houses with lots, and there are a lot of 20 somethings. But it’s also become a really desirable retirement place, particularly for people who want a walking lifestyle but maybe want to live somewhere without stairs.
My mom is thinking about moving to Courthouse when she sells her house rather than look for an active adults type community, because she feels she can get all of that from the neighborhood AND have the great metro access.
And also yes, there are some great places to live in S. Arlington too. When we first got married we lived in a great townhome/condo community called Fairlington. The price was right, the neighborhood had great parks and community pools and grassy areas and big old growth trees. It was a short bus ride to the metro and from our place we could walk to a great bread store, pizza place, ice cream and more. It was lovely. We ended up moving only because the place we had was really too small for two kids once they got past toddler size and were squished sharing a small room, but for anyone reading this in the future looking for a starter home community, I can’t recommend it enough.