I agree that some things are a little hard to make up on the spot, and I really try to avoid that with locations that are supposed to be quite important. Mentioned bullet point writing somewhere in here with examples, bit long, but that is generally how I do it. Seems to convey enough to seem lifelike without dumping hours of my time into a single place. Granted everyone has their style so it might not be for you. I would probably go with your method if a single city or region became the focus for a whole campaign, I'd probably even recommend it specifically, but I find myself filling a world I made up that has roughly 160 unique locations if I only count settlements big and small. It just wouldn't be realistic to build from the ground up for each one, so I tend to favor the appearance of a grand functional city despite having only a handful of specifics. Anyway, if nothing else I'd take a look at my comment just to find the YouTube link I base my foundation off of.