This depends a little on the area and culture. Certainly there's always less variety in a suburb, but there's sometimes good quality and interesting things, there's just not the variety.

Or maybe the places I'm thinking of are "great small towns"? What would you call Pleasanton? (I think it's pretty clearly a suburb, and not terribly much more, though certainly it didn't start out that way...).

Pleasanton the town center? That's a fantastic spot and works very much as a small town. The issue is that bulk of the residents live in suburban (well really exurban) subdivisions well away from it. Their day-to-day is very much just a standard suburban experience, even if there is a lot to love n the actual town center.

People tend to think of "urban" as "City of San Francisco (Manhattan, Chicago, etc...)" To me urban is much of a characteristic. Many suburbs have a relatively urban component at their core. If you live on an actual city grid (no windy streets) with strong mixed uses (that you can walk to) throughout your neighborhood then you're living an urban existence in my book. Or at least non-suburban.

I can definitely identify with people living in central Pleasanton, but you don't have to get far outside the center city before it falls off the rails.

Seems like a reasonable perspective.