I vote for wildflower lawn but I am a tree hugging hippy. I wrote advocating clover lawns here. We've been letting our grass turn into wildflower lawns through natural selection. We don't apply weedkiller or water the lawn and it is now mainly clover and moss. I think if I was somewhere a bit more permanently I'd have some clover lawn with lots of bulbs growing through, which I cold use for cut flowers.