Allan, interesting question! You know, I had to think if I ever came across a nice white Vanda as you describe. Image googling brings up a bunch of white blooming Vandas, thinking strictly Vandas and Ascda in the old sense.
If one now adds Neofinetia falcata, we have another story, in addition there are nice Neo hybrids, I am thinking of Vandofinetia White Crane and other little gems.
Btw welcome to the Orchid forum!
Hmm, the mentioned White Crane is V. sanderiana var. alba x Neofinetia falcata, but that alba form is more or less greenish white, not totally white. Orchid limited has it listed.
Looking around I saw this white Vanda at Hausermann's, not flat and beautiful perhaps, but still pretty?