Are you hoping for plants to plant in the ground? Or are the typical epiphytes good for you?

For epiphytes, Plants I would consider:

Brassavola nodosa
Eulophia (there was a Eulophia growing in the desert greenhouse at the Chicago Botanic Gardens...not sure of species, so you'll have to do your research)

Recommendations I *think* might work but am not sure, so hopefully someone will support or refute:
Vanilla planifolia
Various mexican/rupiculous laelias
Laelia purpurata
Laelia tenebrosa
Rhyncholaelia digbyana
Rhyncholaelia glauca
Reedstem Epidendrums (radicans, etc...)

There is outside, Unprotected, and there is outside under a bit of shadecloth. That layer or two of shadecloth does make a lot of difference.

Where is the nearest Orchid society? A wealth of knowledge will be found there.

Only one or two days a year where the temp gets above 40+ and the only things i have outside (unprotected) are.
Dendrobium speciosum
Dendrobium xdelicatum
a Schom/Cattleya hybrid (The leaves look awful but it flowers every year in the cooler months.)
Reed stem Epidendrums as a clump of garden plants. The better quality ones spend the year in a shadehouse.

Oops! I didn't specify, but I honestly didn't expect any orchids to work in full sun here. That's what I get for assuming!

Yes, epiphytes are as welcome as terrestrials!

I have tried reed-stem Epidendrums here, but they just can't hack the heat, even in the shade. I may try again, if I can find a few to fit my budget, and play some more with soil mixes and pot styles. I left them in their original nursery pots last time. This time, I'll try putting them in a coarser mix in clay pots, and see if the extra aeration and evaporative cooling helps.

I'll have to double check on the other recommendations to see where elsewhere they might have been grown.

Arthur, here's a more detailed outline of our climate:
We usually have about 180 straight days over 40°C, 30-40 days over 44°, and about a week of days over 47°! 35°+ nights can go on for up to two months.
My understanding is that parts of the interior of the northern half of Western Australia have a climate very similar to ours, and many plants from that region do very well here.

The local orchid societies concentrate exclusively on growing the usual Cattleyas, Phalaenopsis, Dendrobiums, etc. in evaporatively cooled greenhouses. I'm hoping to develop a few kinds as landscape plants, quixotic as that may seem!

Thank you both for your input!

Any other ideas out there?

Kevin : )

Try Eulophia petersii, if you can find it.
It has blue-green, hard, succulent, upright leaves, with finely serrated margins, and tall inflorescences.
Native to eastern and southern Africa and the Arabian peninsula.

There's additional discussion of this species elsewhere on this forum.

That's an awfully long period of cold nights for tropical orchids, but some of the more northerly subtropical Mexican species and their hybrids might work. Laelia anceps and its hybrids are known for tolerating extremes, possibly some of the Mexican Encyclias as well. I think your winters are too cold for the Brazilian species to thrive, though. I don't know if the Carribean Schomburgkias and their hybrids could take that much cold, but they could certainly stand the light and probably the high temps, though "dry heat" is a friend to no epiphyte. :)

Your area is more extreme than Southern California, but closer to that than Florida and the Gulf Coast, so nurseries there are probably your best bet for advice and plants. A few that come to mind are Santa Barbara Orchid Estate, Cal-Orchid and Andy's. "Temperature tolerant" is the general buzzword for plants that will grow outdoors year round out there; some of them might be suitable for your area as well.

You could try some of the "Mule Ear" Oncidiums. I think they might make that cold period if you could get them into a micro climate near a stone or brick wall. Maybe.

If it's too much for Epidendrum hybrids, not much of the rest will work. You stand a much better chance if you give them some sort of shade. I would plant a few fast growing trees first and then you will have a lot better options. - Ian.