If you are often annoyed when your grass starts to go brown after a week or two of hot weather, perhaps you should look into sedges. Sedges look like grasses, but they're not. Their leaves are wider, a little tougher, and sport a keener edge. And they stay green and perky long after your grass has thrown in the towel. 
 
 
 
Now, you might not want to walk on these guys too much (keen edges, like I said), but for those areas off the path that are crying for some lush greenery even in the summer, sedges are the ticket. 
 
 
 
Many sedges like marsh and streamside habitats, but chamisso sedge is an upland sedge that grows in surprisingly dry areas in our grasslands and forests (it can handle a lot of moisture though). In the late spring it develops a clustered flower spike that will persist through the end of the summer. It has a bunching habit but will spread slightly through rhizomes. 
 
 
 
Although it can tolerate very dry sites, I recommend giving it some extra water for best performance (think swale up on a grassy hill...just slightly more water). It's a great backdrop for showy floweing species such as blanketflower, wild bergamot, penstemon, Oregon sunshine, sticky geranium, and sulphur buckwheat.