Panicum 'Shenandoah' is one of my favorite grasses - medium height, pretty delicate flower heads, and doesn't flop at all. Mixes well with many medium height perennials. Doesn't get much color in the shadier locations though. Other tall grasses that grow upright for me - Miscanthus 'Gracillimus', Miscanthus purpurascens, Calamagrostis Karl foerster and Overdam, other Panicum virgatum cultivars (Heavy Metal, Rostahlbusch). Panicum 'Cloud Nine' is very tall and flopped a little, perhaps because it was growing in partial shade.

Some of the small 'The Blues' I ordered last fall from SRG bloomed and these were very small plants so you might be surprised after all. I was. I decided to wait until Fall to place my order from Jelitto since everything I now have decided on is cool season. I definitely have my mind set on the European Stipa 'Pennata'. And some of the other Stipas. Have you ever grown the 'Pennata'? Its planned to be my replacement for the Elliot's Love Grass which is already putting out volunteer seedlings and its only June of the first year. Now, there is invasive but then there is INVASIVE.

'Blue Heaven' is MinnBlueA.

Our rain is unpredictable. Technically we are listed at 30" per year but........ That depends. We have been in that same drought you are probably in for the last several years but sometimes we get a lot so its hard to plan what to grow, its crazy making. This spring was real wet and I had some plants suffer. I'm on a slope with good drainage so that helps. The last few summers had straight endless weeks of daily 100+ temps with no rain almost all summer. We also have high humidity during periods in summer, it depends on what the weather decides to do to us, we are at its mercy in so many ways. I don't do hardly any watering here. Its survival of the fittest but I will relent when weeks have gone by on certain plants or if I am establishing something new. All the kinds of Miscanthus need supplemental water in summer here. The ones around here died in the last few years unless they were irrigated and many of them looked like crap from the heat. The Pennisetum grasses need a lot of watering or else they look bad. I avoid both of these thirsty grasses. Since we have been so dry in the last several years, it should give a good idea of what will do OK for you there on such little rain, but 5" is extreme, ouch! The muhlys all look great without any supplemental water, including the regal mist. I read that M. rigens thrives on drought. I believe it, mine grew fast in that dry heat and was as healthy looking as you could ask for, same for the Pine Muhly. The M. lindhemeiri gets much bigger with more water but did fine during the drought. These really vary in size a lot depending on conditions. I had one growing by the air conditioner drain and it was a monster in size while the ones growing dry were much smaller. In Texas where the drought was much worse, some of the muhly's went dormant and looked awful in 2012 but I think they came back OK from what I read on the Texas Forum. They seem to be programmed to withstand the drought. I know you would do very well with the Sacaton wrightii. I bought 4 of those improved huge sized ones for a 'hedge" that they sell at High Country Gardens and didn't like it. It grows very very fast but the leaves are sort of wide and it wasn't to my liking like the unimproved ones I grew from seeds and replaced it with. I also bought that Muhly lindheimerii/capillaris hybrid one called 'Flamingo'. Its gorgeous. As an isolated specimen that improved Sacaton might do well for you if you want a TRUE MONSTER Grass. The Ravenne grass seems to be made of cast iron. These cook along the highways and look fine, no watering. They are common along with Crepe Myrtle and Chaste Trees which all seem to be indestructible here. The grass stands real straight and very tall. We are so windy here, most of the trees trunks lean toward the north, but not the grass. I always consider the highway test as 100% reliable on drought hardiness. All of the native grasses you mentioned are also used a lot in that way. The Mexican Feather Grass is often planted with pink blooming hesperaloe and thats a nice drought hardy combination. The Switch Grasses are used too in mass plantings along the roads and seem to do fine with little water here. I think they will do well either wet or dry. I'm so jealous you got to go to Plants of the Southwest. I would love to visit the nursery sometime. I have two desert Four O'Clocks I started from seed I got from them last fall. I have tried the Feather Dalea seeds without luck four years now. I can get them to germinate but then they die. I have good luck with various penstemon, Russian Sage, Lantana, Blackfoot Daisy, Desert Marigolds, Salvia Greggii and Flame Acanthus but not Agastache. I see other people growing it but mine always die. I don't know why. I have lots (too many) of kinds of cactus and cold hardy agave but the cats don't seem to mind them. The Apache Plume gets real thick if you prune it back hard in spring. Its very ornamental, at least to me, but I have weird taste or at least I seem to be in a tiny minority when it comes to plant tastes. Other ones I have that I love are Mormon Tea and Winterfat, you probably have that growing wild there too. I like the looks of the silver nightshade a lot, maybe I should investigate it a bit more. I don't want invasives.