Diagonal! Haha!
I brought the floor 1/4 inch up already on the low spots with the hardibacker. There is another 1/4 inch to go. I did not want to do it all with thinset under the hardibacker, as I read that it has its limitations on how thick you can put it on there due to shrinkage. We will see how it goes.
Reading more, people claim that larger tile makes a smaller room look lager. I don't know. 6x12 isn't exactly small. Maybe some more of you chime in. I like the idea of 6x12 and going slow, so I can always jackhammer the last section if I have a bunch of lippage.
How wide should I plan my grout? I read wider is better for the idiot DIYer.
G