Hey Zach,

1- I agree with Kell here, you gotta get the size straight with the client firsthand. In my book, size determines price so, that's a must have before starting. The other thing is that resizing (up or down) will mess your lineart and your labelling. I'd say it's something to set in stone for every project, I remember reshaping a map for a client because he changed his mind for the format and it unbalanced the whole map which was not pleasant to fix. My advice, aim for hardcover size (6x9 inches) and add a 1/2 inch margin on each side for breathing purpose and to avoid cutting of your map. You also have to consider the map will be reduced for some editions and label accordingly.

2- I've recently been confronted to the gutter problem and just added a colored mask to my map covering one page. After that, discussions with the client allowed me to avoid putting labels or important stuff there or move what might me hidden. The issue might be with labelling consistency as you will end up breaking some rules (position of a city name near it's marker for instance).

3- Never chose the size for your client, it's choosing the price for them. Propose a price for both sizes (simple page or double page or A5 or A4, whichever you fancy) but it's their map, their choice (their money). And for your last question, see 1-, it's really a matter of labelling because that's what suffers the most from resizing.

I look forward to seeing what you come up with

Cheers !