I lent the proof of the old layout to my sister, explaining to her why I was changing it. She opened the book and immediately said, "Oh, yeah." And of course it was something I hadn't really thought too hard about, which is that, unless it's oriented to children, a book with really big margins doesn't really look like a book--publishers also want to save paper, staff time, and therefore money by keeping the margins narrow, so readers unconsciously expect that.
CreateSpace bounced back the large-print edition. It's interesting because apparently they do do some proofing, and their concerns are twofold. The first is that, although I describe the project as "Trang (large print edition)" the title page just says "Trang." My initial reaction was, Well, doesn't the fact that it says "Trang" in very large letters give you a clue? but then I realized that they're just trying to make sure I didn't accidentally submit the wrong interior, so now the words "large print edition" appear both on the cover and the title page.
The second concern was that there was a problem with pagination. I doubled-checked the chapter files, and the page numbers are correct, so at first I was thinking that I had just screwed up and bundled the chapter files in the wrong order. But then, looking through the layout, I found another problem (and if this was their concern, it was a very good catch indeed, and I commend them for it): Unlike in the e-book, where I actually call the first chapter "Chapter 1" and the second chapter "Chapter 2," in the hard copy I just use chapter numbers. These numbers appear in the upper right-hand corner of the page, fairly close to where the odd page numbers appear (there are no page numbers on the first pages of the chapters).
In the regular edition, the chapter numbers are a different font, and they are MUCH bigger than the page numbers, so there's really no possibility for confusion. But in the large-print edition, everything's the same sans-serif font, and the page numbers are very big. Also, both page and chapter numbers have been bolded, because you're supposed to do something like that to things that are not part of the main text to help distinguish them visually from that text.
Although I did enlarge the chapter numbers, I didn't enlarge them enough, the end result is that the chapter numbers look an awful lot like the page numbers--which is obviously a problem you can't ignore in an edition that is supposed to be easier to read. Lucky me, it looks like I can alter the chapter numbers without screwing up the rest of the layout. So that's what I'm doing right now!
ETA: OK, I finished this and uploaded it again. I'm hoping the numbers are different enough--I used Arial Black for the chapter numbers (everything else is regular Arial). I thought about switching to a different sans-serif font for the chapter numbers, but it seems like the other fonts I have don't actually have sans-serif numbers. If CreateSpace kicks it back again, I'll just go with Copperplate Gothic (the font used on the front cover) and hope that the enormous font size makes up for the presence of serifs.