In my zone 8, I grow all but the very light, chartreuse or gold foliage heucheras in full sun. IME, shade unnecessarily stunts their growth and washes out the color (purples more bronze than purple; golds/toffee colors less intense; heavily veined or marked forms lose their markings). But my zone 8 is pretty far north and sun intensity is much different than elsewhere in the country. I think in hotter climates, morning sun and afternoon shade (or lightly filtered/dappled shade) may be the best setting.

Rozanne geranium really works best as a weaver around good sized perennials, grasses, and shrubs. The first year she may stay in a clump, as she did for me, but after that she puts out long stems and likes to climb up, over, & between other things in your garden. She can be cut back hard to keep her in bounds (sacrificing a few weeks of blooms) if you prefer, but it is easier to let them do their thing. I have 9 in my south facing mixed shrub border. As a result they get some shade from the other plants, but no overhead tree or building shade and they seem to love these conditions. For me they start blooming after a lot of my other geraniums, but continue blooming until hard frost. My garden is heavy clay and wettish but tends to be somewhat drier around my big shrubs and grasses where six of the Rozanne are planted. The other three are doing just fine in a much wetter area, but these divisions have never gone through winter there yet so I'm not sure if they will overwinter in a wet area. Biokovo is planted in an open spot in a sunny daylily bed, the small grayleaf geraniums (cinereum Splendens) are planted along the edge of the drier patio bed, shaded somewhat by some of the other plants, and the various sanguineums, along with some Rebecca Moss (oxanianum) and Wargrave Pink (endressii) are in pretty much full sun in an island bed centered by some tall phlox and offset by a small Hinoke Cypress. The island bed started off as a holding area for sunlovers - but you know how that goes...:~)...anyway the geraniums, all at least 3 years old now & never replanted elsewhere, don't seem to mind the sun (at least in zone 5).

I have Obsidian and Blackout in full sun. The Obsidian (3+) look great all summer long. Blackout is fine, but I think it looks enough like Palace Purple (bronzy rather than purple) that I will not go get more. I have a Midnight Rose in same location: it also look very good. Also Stormy Seas, though that does not seem to do as well there. I've decided that Obsidian is one great heuchera. I'm going to give up on Plum Pudding for good, and put Obsidians in where all the Plum Puddings died (part sun, not full sun).

I am not sure if the sun is much hotter in your zone 7 but they seem to be doing okay in my zone 5 plus weather and we get lots of summer weather in the 80s F. plus I do not know what the names of mine are anymore as I usually grow hosta and shade gardens but these seem to be doing great in the two years I have had in the sun. I needed something on the west side of my house and they look better then my shade ones now. They do get lots of water so maybe that is the secret Please excuse the mess, we have had it very windy the past couple days and I am still cleaning up Faye