Okay, from the original Dune videogame (PC/Amiga) I got a list of sietches. However, these are mostly combinations of names from the books. For example, Sietch Tabr was Stilgar's sietch, and Tuek's Sietch was also referenced, as was the Habbanya Ridge, the game uses Sietch Tuono Tabr and Sietch Tuono Tuek as well as Sietch Habbanya Tuek and Habbanya Tabr. So it depends on what we're going for. I'll post the list here to see if it's something we want to use. Here goes:
Carthag Tuek
Carthag Harg
Carthag Timin
Carthag Tabr
Carthag Clam
Carthag Pyons
Carthag Tsymyn
Tuono Tuek
Tuono Harg
Tuono Timin
Tuono Tabr
Tuono Clam
Tuono Pyons
Tuono Tsymyn
Habbaya Tuek
Habbaya Harg
Habbaya Timin
Habbaya Tabr
Habbaya Clam
Habbaya Pyons
Habbaya Tsymyn
Ergsun Tuek
Ergsun Harg
Ergsun Timin
Ergsun Tabr
Ergsun Clam
Ergsun Pyons
Ergsun Tsymyn
Oxtyn Tuek
Oxtyn Harg
Oxtyn Timin
Oxtyn Tabr
Oxtyn Clam
Oxtyn Pyons
Oxtyn Tsymyn
Sihaya Tuek
Sihaya Harg
Sihaya Timin
Sihaya Tabr
Sihaya Clam
Sihaya Pyons
Sihaya Tsymyn
Tsympo Tuek
Tsympo Harg
Tsympo Timin
Tsympo Tabr
Tsympo Clam
Tsympo Pyons
Tsympo Tsymyn
Haga Tuek
Haga Harg
Haga Timin
Haga Tabr
Haga Clam
Haga Pyons
Haga Tsymyn
Celymin Tuek
Celymin Harg
Celymin Timin
Celymin Tabr
Celymin Clam
Celymin Pyons
Celymin Tsymyn
There may be more or less of these as I just extrapolated from what I knew. I'd have to play the whole game again to get it exact. Anyway, that's one idea. The problem is that while most of these names are partially real, they get repetitive.
Here's where the names I know of came from:
Carthag - Harkonnen megalopolis and their capital on Arrakis
Tuek - Tuek's sietch (from the book)
Tabr - Sietch Tabr was Stilgar's sietch
Habbanya - Habbanya Ridge sietch also named in the books
Tsympo - There's a Tsimpo on maps of Arrakis, though it's more of a province
Sihaya - Sihaya Ridge, south of the Shield Wall
Harg - Harg Erg on Arrakis maps near the Polar Sink