Dan,
Sounds like you have the same 'minimalist' maintenance policy for your lawn that I do! The house I live in was built almost 60 years ago, so I figure the grass should be pretty well established and drought tolerant by now. It has gone very brown during prolonged droughts but it always recovers.
The main hassle I have is two gigantic 150 year old oaks that shade most of the lawn (but also the house, so I rarely need AC!) which make grass tough to grow in some spots. So long as there is a bit of moisture, moss and violets grow in those bare areas, which is fine with me, adds a bit of variety and color to the lawn!
However an ex girlfriend of mine insisted the moss and violets I had in those bare areas were weeds I should eradicate and talked me into getting a lawn service to try to get grass to grow in. So they sprayed weed killer which killed everything but the grass but couldn't get grass to grow in those areas so matter what, so they were just bare ground. So I dumped the girlfriend, cancelled the lawn service, and this spring the moss and violets have returned
I building a new house, and once the sod is well established I'm planning on giving it only enough water to survive, and let all the less drought tolerant blades die and be replaced by hardier blades in Darwinian fashion. Not because I am trying to make my lawn F&F, but because I don't want to be bothered to water the damn thing everytime it hasn't rained for a week like everyone else in the new neighborhood appears to do. Plus it may serve as a hint to the super of the course it overlooks!