umm, I have to do some math to see what those temps translate to (there is an app here somewhere...). gigantea is a slow grower normally, and if it was in a more 'tropical' environment at krull-smith, both plants may be rethinking their priorities a bit. they both also come from environments that are very uniform year-round in the amount of light they get, the amount of moisture they get and even the average day, night and differential between the two, all year long (very stable). the temps look okay though 64F(18c) is at the bottom of their limit, really so if they are as wet as they normally would like to be in nature (wet with tons of air movement especially for gigantea) and get down to 64 that may check them just a little.
I have plants mostly under lights here in upstate ny (part of the temperate cloudy region of the world), and things did better when I set my lights to 16 hours and left them there. there is some sunlight getting in but the lights are on before and after the sun has shown itself. both like tons of humidity, so though I know over 60 is good for canada in winter (and here as well) getting it alot higher with lots of air movement will greatly increase that as well. I had read that gigantea liked shade, but then read in the baker's culture books that it grew in the tops of trees in it's area, so for a phal it could take a fair amount more of light. of course that's a fair amount for a phal and not a catt, but they can handle year-round brighter conditions than most phals (without any direct sunlight) and having longer daylength on your lights will increase the total volume they are getting and equal that. giganteas are also supposed to be touchier with chemical fertilizers, i've read about using weaker and fish emulsion types of fertilizers (natural types) to the leaves.
most people here that have posted their success with violacea live where it is pretty humid and gets lots of air, and of course warm. you might want to check out your water, and also what type of media you are using. I had switched alot of things into chc's and for a while things were looking okay but then many aren't. (salts) you don't mention what they are potted in and the water type.
if you up the light a few more hours and raise the humidity a bit more and have solid air movement and everything else is where it should be (and you do fertilize) then they should start growing. if not, maybe they are still sulking or something else is contributing
http://www.orchidculture.com/ is a great site for purchasing and downloading very detailed culture sheets, based on meteorological information from at or near the sites the orchids grow at. there are free ones you can download and check out, they are very eye-opening!