Yes. those plants grow gangbusters in vb with no thoughts of protection. robusta burn below 25 and die below 18. they need protection and even with protection are suspect at best due to susceptibility to disease. Filifera will be about 5 degrees better.

Oasis, did you see the pics of a robusta I posted in this thread?

http://forums.gardenweb.com/forums/load/palms/msg0700351218983.html?14

To me, Washingtonias are even less cold tolerant than livistonas in certain situations, and they are definitely less cold tolerant than all of the other plants you mentioned. They will likely get some foliage damage even with protection, but they are really fast growing which is why it's so valued as a cold hardy palm!
Good luck with your washy! I want to try one in the ground someday, but I have had bad luck with them as potted plants.
-Alex

For me, it has been the reverse in terms of the cold hardiness. My containerized Washys don't show nearly as much cold damage as Livistona chinensis. The latter seem really borderline (between cold hardy and needing to come into the house). As for you lack of success with Washys, I find that very surprising given your experience with palms. They are not, however, a really good "houseplant" which is why mine never get into the house past the seedling stage. They are just too massive and sharp for inside for my tastes. The tubs get wheeled into the garage in December and come out in March. They get watered a handful of times in winter. In summer, they get full sun and get hosed down once or every other day depending on temps, rainfall, etc.. You might need to use a larger container for them.

Exactly-this is one palm that likes to spread it's roots,if
it can't,top growth is stunted indefinitely.

I use a thermocube in mine on 35F/off 45F no brainer-love it.

The one thing with Washys is you have to protect the roots,
they are not tolerant of cold/moisture and if there is root
kill in winter/spring it goes back to the plants base and
brings all the nasty fungus and what not with it to finish
off the palm.

I put down 6" mulch all around mine and this is spread out
farthur from the palm every year to accommodate the roots-

Best of luck to you-they are very rewarding and in the 3rd year
I am seeing the growth that we have all read about
and I am really enjoying watching it blast leaves out now...

maybe over one a week now-no kidding/exaggerating.