Almost any cool season grass will suffer in the summer heat if it doesn't get enough water. KBG probably needs more water to stay green than some of the alternatives. Some fescues can get by with somewhat less water than KBG, but they'll still go dormant in the summer with no water. If you want a cool season grass that will stay green with no additional water, I think your best bet would be a native grass like western wheatgrass. Despite the name, it does extend as far east as Ontario. The drawback is that it is somewhat blue green instead of the green of a traditional lawn grass. It can also be rather difficult to get started. If you want a traditional lawn grass with a traditional lawn grass color, you'll need to water it to keep it green in the summer. If you don't mind a different color, something like western wheatgrass may do the trick.

I'm growing hosta, astilbe and lady's mantle from seeds I harvested from my own plants and winter sowed. Pulmonaria (lungwort) is another shade lover, as is black snakeroot, Japanese painted fern, bleeding heart, Japanese sedge grass (carex), and toad lily (tricyrtis). My full shade area is packed with all of the ones mentioned so far on this thread. Brunnera (Siberian bugloss) 'Jack Frost' is going gangbusters in that bed as well but I've never had any volunteers and I hear it's not worth trying to grow from seed. They're gorgeous plants for the shade but they're pricey at the garden nurseries. The one I have is 'Jack Frost.' Best way to get more of them is to grow one & divide it every 3-4 years. Another one that's pricey but does produce seeds is Lenten rose (Hellebore), so named because it blooms during the season of Lent, very early. It's evergreen too. I WS coral bells seeds I got in a trade but got zero germination. I may try to harvest seeds from my own plants this year and try again. I figure since coral bells were the ONLY seeds out of 44 different, new perennials I WS, I should probably try at least one more time. The hosta I WS are doing great but they're not variegated like the parent plants. That's the downside of WS hosta seeds--chances are you'll get plain green ones but they're still free plants! They take time to get any size on them--3-4 years minimum. They don't need cold stratification--I grew some last summer in a sunny window, wintered them over and they're back up again this year, albeit still small. For moist shade, turtlehead (chelone) is nice. I WS seeds and have some nice size sprouts. I WS the white since the butterflies supposedly prefer them over the pink. Don't forget hydrangea--the "hydra" part of the name is Greek for water. They want some shade too and there are gorgeous new cultivars coming out all the time. Lamium makes a nice groundcover for shady spots along with ajuga if you don't mind it spreading everywhere. Creeping myrtle seems to thrive wherever it's planted--I've got it growing in full shade, full sun and everything in between.

So far it looks like you're getting advice from Yankees. Growing fescue here is a waste of time and money. It should be criminalized for wasting water. It looks like you already have St Augustine. No other grass could look that good in there. A close up photo would be nice - from 3 inches away - on an overcast day - with a clean camera lens. All you have to do is water St Aug and it will spread 15 feet per year. That might look like a lot of shade, but St Aug can handle a lot worse than that. If you want to get it started in places where it isn't already growing, buy a piece from the local nursery. They might try to sell you Floratam. That's okay but Floratam does better in full sun than in the shade. There are other varieties that do better in that much shade. If Floratam is all they have, use that. Just get a few pieces and put it down. Water those pieces by hand 3x per day until they knit into the underlying soil. You'll notice the grass growing up tall when it is knit in. Here's how to water. Watering: Deep and infrequent is the mantra for watering. This is for all turf grass all over the place. Deep means 1 inch all at one time. Put some cat food or tuna cans around the yard, and time how long it takes your sprinkler(s) to fill all the cans. Memorize that time. That will be the time you water from now on. My hose, sprinkler and water pressure takes 8 full hours to fill the cans. Your time will likely be less. I like gentle watering. As for watering frequency, that depends on the daytime air temperature. With temps in the 90s, deep water once per week. With temps in the 80s, deep water once every 2 weeks. With temps in the 70s, deep water once every 3 weeks. With temps below 70, deep water once a month. Note that you have to keep up with quickly changing temps in the spring and fall. This deep and infrequent schedule works in Phoenix and in Vermont, so it should work for you. The reason for deep and infrequent is to grow deeper, more drought resistant roots and to allow the soil to dry completely at the surface for several days before watering again. If it rains, reset your calendar to account for the rainfall. I strongly recommend an oscillator sprinkler for your rectangular lawn. Get the turbo oscillator. They don't all say turbo on them anymore. Some say gear driven. Just don't get the one with the exposed mechanical linkage. Those are bad from the factory. I've had gear/turbo driven oscillators last for years and years. $20. For St Augustine mulch mow at the mower's highest setting every week or two (or three). Taller grass develops deeper roots that get nutrients and moisture from deeper down. Fertilize 3x per year, Memorial Day, Labor Day, and Thanksgiving (or so). Or you could fertilize with an organic fertilizer now or any time. Give that 3 weeks and the grass should look 100% better in color, density, and growing speed.

If it gets at least 5 hours of sun, consider a summer blooming clematis on a trellis. Then you can cut it back for the winter and still have the trellis as an ornament, perhaps with lights twined onto it. Hydrangea Tuff Stuff is about the only big leafed Hydrangea that is hardy enough to bloom for me, and it is very consistent, blooming every year I have had it. Some of the Viburnums are happy in a fair amount of shade, but you would need to avoid the types that are particularly susceptible to Viburnum beetle. Cornell has a listing of those that are most and least vulnerable. You could choose a Rhododendron, either evergreen or deciduous. Besides the spring flowers, the deciduous rhodies often have nice fall color and the evergreen ones will give you a winter presence.