I planted evergreens here in northern VA as a screen and came to realize that they weren't really what I wanted and didn't screen all that well anyway. I just had them taken out and I replaced them with native flowering trees that will, in a few years, provide all the screening I could want for the three seasons we use the patio and deck. In addition, we'll have the advantage of beautiful flowers. I have several shrubs (hydrangea paniculata, flowering quince, etc.) around and among the trees and will fill in with more as well as hostas, ferns, annuals for color. This will give you a nice layered look and excellent screening except in winter when you won't be out there anyway...or will you?

I think I spotted a few willow screens at Loblaws. But you probably would be more successful if you visit garden centres. Hydrangeas will work in dark areas but I'm not sure how it will work in a mucky and clay soil. However it is the ideal plant for dark corners. Whatever plant you choose, you need to condition that soil to provide good drainage Also choose mature plants so that it can reach whatever sunlight that's available. Vines that require regrowth from the ground each year, will not work. If the top area is sunlit, you can probably install a mature wisteria.

I have 2 simpson stoppers and mine are slow. They are small leaved but not really hedg-y. They want to be trees with interesting trunks not bushes. I have mine planted in an informal hedge between our house and next doors, mixed in with native coffee and a variety of other natives including porterweed, hercules club, wild lime and many others. A new choice I've just added in the hedge to block the view is jatropha. It's bushy,flowery, butterfly beloved and will get tall. It's my new favorite in the hedge.

Usually, ready-made lattice looks super cheap and tacky. There are exceptions which usually require some sort of heavy framework & tasteful decorate details. Beefier custom lattice -- also with good details -- has the potential to look much better. It would be very unlikely for vines to just die unless they are being given NO care at all or being treated badly. If one vine in a section dies, then adjacent vines can move in quickly to cover the bare spot. I didn't mention, but since a perennial vine can take a little time to cover solid, annual vines are useful in the meanwhile to provide quick (6 weeks) solid cover. I have had great luck with moonflower vine on this count. Heavenly Blue Morning glories can be used and look great but they tend to hang toward the top and leave the bottom bare. Don't use any temporary vine that reseeds itself. 'Grandpa Ott' morning glory is like this and is the weediest damn thing ... still sprouting 4 years after the original was killed.