Well the climate here in Seattle is quite different than Cincinnati. But here is what works for me: 'Jethro Tull' Coreopsis. I have tried many varieties, this is the only one that is actually perennial here. The only problem with it is the dead flowers turn brown and hang on, and since it blooms from early summer until frost, that is a lot of dead flowers. There are two great ways to deal with this without deadheading daily. The first is to plant it where nobody sees it up close. Then the bright yellow flowers are what you see and the small brown deadheads are simply not seen. Done this way the only care it needs is cutting back once a year. Or just twice in the summer cut it back to about 8" tall, this takes a minute, within two weeks it is blooming again. For an unused area of the yard I think a plant like this would be great. 'Jethro Tull' is extremely drought tolerant. Mine is in hideous clay/builders rubble and severely neglected, but it does not seem to mind. I have never tried 'Evolution' so I can't say if it would be similar.
Coreopsis 'Jethro Tull':
Here is the same area in May, just before Jethro starts blooming. This is Geranium x magnificum and Geum 'Totally Tangerine', these are also extremely rugged and tolerant of neglect.
