Plectocomia is a small genus of rattan palms from south-east Asia.  Like Calamus and Daemonorops, it is very spiny and climbs into trees to reach the sunlight.  P. himalayana, recently introduced by Gibbons and Spanner, is said to be the hardiest species, coming from moderate elevations in the Himalayas.  There are isolated reports of it surviving very cold temperatures and being much hardier than expected (for example, -10°C/14°F in Belgium), so it may be that this species is hardy in milder parts of the Pacific Northwest, although it will be a while before we really know.  In any case it would certainly not be unusual for a rattan palm to have more hardiness than what it necessary for it to survive where it is native.  P. khasyana, from the Khasia Hills in northern India (home of Trachycarpus martianus) might also be worth growing, if for no other reason than its 33' long leaves with grappling appendages extending much farther from the tips.  P. himalayana is much more modest, but still impressive.