They sell large troughs that serve a similar purpose - some that are actually quite tall for more eye level planting. Or you could attempt to make raised beds along the driveway using stones or other materials to define the raised area. With respect to the wet site - assuming you have good drainage in a container placed there, there are some shrubs that grow well in wet locations and should be hardy in your area in a container - eg., the shrub dogwoods (Cornus alba, etc). Clethra alnifolia (summersweet), many willows (Salix spp. including the Pussy Willow - S. discolor, etc.)., and witch hazel (Hamamelis spp.). In any of those cases, I wouldn't put the container right under the deluge, but those shrubs can take cold/wet, and in your case, with them being on concrete and south-facing, they could receive a microclimate that can protect them somewhat, particularly if you get snow in that corner. There are a few perennials that might be able to take that like dicentra and most of the mints, but again, you would want a good container mix so that you don't end up with a water garden there... Which is another option by the way - where the full sun could give you some nice water lily blooms. ;-)

Thanks for the responses and ideas. boxofrox, the picture is beautiful. I love the combination. bboy, I think you're right. A combination would look really nice. I've never had bergenias before. I'll check those out. I do have quite a few heucheras and love them. Nearby plants are hellebores, saracocca, various ferns, azaelas, pieris japonica, camellias, and I'll have hanging fuschia baskets. The planter box is in the spot that gets the most sun in the yard, a few hours in the late morning, early afternoon. I really appreciate any help!

Stacey I like a lot of your ideas and have had some of them myself! . I’d like to widen the walkway but it’s flanked on either side by our irrigation system. I’m thinking it could be cost prohibitive to adjust it, but it’s on my wishlist. We have about 8 crape myrtles in the front and back yard I’d like to remove too including the ones in the flower bed you mentioned. I like crapes typically but I feel like these have gotten too tall and they are constantly dropping bits of leaves and blooms all over the yard!

These are rough photos of one example. They will be sitting on a concrete ledge directly above brick wall, so wieght should only be a min r factor. Securing to a roof is a a concern but only a concern if it is possible to find something perenial (and attractive) to grow that requires little mainteance. I would have about 5 of these spaced to cover 2 coornery of garage. I could start plants at ground level so I could water until established. Sorry for delay on pics. Weather in Midwest has been disgusting and I didnt want to hoist one up just for a photo opp.