I actually had thoughts about Dorne for quite a some time and as I can see discussants here have quite alike thoughts too, so I will write my suggestions for Dorne too. As I'm not such a great specialiast on Mediterranean and Desertal cultures, my suggestions maybe not entirely correct, but I hope they will be of some use anyway.
First of all, I want to talk about natural environment. I totally support making canon-accord stony desert of Eastern Dorne in contrast to sandy desert of Central Dorne. Being in line with suggestions above I think that this desert shouldn't be just a barren land, but should have some vegetation as well. The most defining aspect of Eastern Dorne's environment in my view is that it is very seasonal, with distinct dry and wet seasons (aligned with uneven seasons of the Planetos, I think the dry season can fall onto summers, while wet season onto winters, akin general seasons in real Mediterranean). During the wet season, wet air masses go to Dorne from the region of Summer sea directly south of Narrow Sea. In this sea region, Tropical cyclones are orginiating (Stepstones archipelago itself is famous for being stormy). The wet air masses fly over Eastern Dorne giving some rain (and occasionaly storms), but mostly they are catched by uplands north of Greenblood basin, as well by uplands where Scourge and Vaith are originating. Here, in these uplands, wet air masses turn into rains, that make the uplands quite green all the time, but especially during wet seasons, when rain fallen in these uplands turns into numerous small streams going downhill to feed Greenblood and its tributaries, significantly raising its water level. As such, during wet seasons, the stony desert of Eastern Dorne mostly turns in quite habitable, green lands, while being dry land during dry seasons, when all the numerous small streams are dry rivercourses as well and rain is scarce. (This is different from sandy desert of Central Dorne, where rains are much rarer and unregular, because Summer sea south of this part of Dorne is quite still all the time). As such I propose making uplands, first of all, eastern slopes, where Scourge and Vaith are originating, generally greener, as due to elevation, even scarce wet air is catched here even during dry seasons, and that feeds Scourge and Vaith all the time, through the two (and Greenblood as well) are quite small rivers during dry season, in contrast to being real rivers during wet season. Also, I think that Stepstones, Broken Arm and strip of coast from Greenblood mouth to Spottswood (so, including Sunspear) should be not deserts, but generally mediterranean coastline, quite green even during dry season, covered a lot by farms and orchards, supporting towns of Plankywood and Shadowtown with fruits and livestock, while grain comes mostly from irrigated Greenblood valley.
As our timeline is somewhere in early autumn, I think general Eastern Dorne landscape shoul be dominated by dry lands, rowed by dry watercourses of streams from uplands feeding Greenblood during wet season, with dry-sustainable vegetation here and where, while the coastal area from Lemonwood to Spottswood, alongside with Broken Arm and Stepstones, should have pretty Mediterranean landscape, like the Tor coast.
Now, to more cultural and historical aspects. As it is evident in canon, prior to Rhoynar arrival, Dorne was dominated mainly by lords based in "greener", less season-affected lands, like Yronwood and the Tor, while Jordaynes of Godsgrace sustained on all the yield that Greenblood basin could give by "primitive" farming. Martells, based on eastern coast of Dorne, quite green (as I suggested above) were self-sustained as minor lords, but couldn't be anything more with such small economical powerbase. The arrival of Rhoynars brought not only centralised force, by alliance with which Martells became the major house, but important technologies as well. Just like Romans and Arabs brought their aqueducts and norias to Spain, Rhoynars brought advanced irrigation and water-management techniques from their homeland basin of Rhoyne. These technologies, alongside with general population influx, enabled to turn Greenblood into a much more productive agricultural area, with rational irrigation, utilising river's overflow during wet seasons, as well as making farms and orchards in coastal strip around Sunspear (and in Eastern Dorne in general) much more productive. This turned previously backward Eastern Dornish lands into a far more prosperous lands. Increased agricultural yields and proximity to Essos for trade, sparkled the growth of large settlements and towns in Eastern Dornish coast. All of these served as effective socio-economical powerbase of Martells and their immediate vassals, so the house of Nymeros Martell was able to keep its dominant position in Dorne for all the centuries, taking revenge on all the houses who mocked them in earlier days.
As such, cultural landscape should consist of following: as Azulejo suggested, the lower Greenblood valley is dominated by irrigational works, channels and reservoirs, mainly for produce of grain in my opinion (wheat and barley, but maybe even rice as well), with multiple villages along the river and Planky Town in its mouth; eastern Dorne coast should be dotted by villages with orchards and farms (with livestock!) with Sunspear agglomeration as main settlement, while inner, drier regions of Eastern Dorne should have small villages here and where, with inhabitants waiting wet season for starting agricultural works and mainly grazing small cattle until then.
P.S. Why Martin hadn't named Greenblood as [new] Little Rhoyne, this name could fit it so much.