I like your idea, CapnG. However, since they are off by about 2 mm, that will leave a 1 mm gap on either side between the side of the tiles that print correctly and those that don't. And if I had, say, 4 tiles put together (2x2), that would leave a gap of 2mm in the middle. That would be noticeable.
The hallways don't bother me, but the square tiles do. I know that it doesn't seem like a much, but, depending on how the tiles are laid out, I can see some rows of tiles in my builds being off by 1-1.5-2 cm. My first project was going to be 3 level sewer system, 7 tiles x 7 tiles. Later, I was going to add 3 more levels of a street/elevated highway scene above--this was to have a good build for some Mordhiem-esque game that I'm wanting to get my son into--and what better way to WOW him and perhaps some of his friends.
I guess I could photo shop the files and try to compensate, but that seems to be an awful lot of effort for that . . .
Since you have the same issue, CapnG, do you have any photos of some large builds (6+ tiles on a side) that you could post and let me see if there really is an issue? Maybe I'm trying to be too much of a perfectionist, but when you have such beautiful artwork, how can I not.
Thanks for all of the advice everyone has given me and Thanks in advance for those who still feel they have something to contribute.
BTW, I have an HP Photosmart C4440. It's a great printer except for this problem. So if you're thinking about getting one for WWG builds, you might reconsider . . .