We’vet just finished the e-book guide 4 Perfect Days in Buenos Aires. It was a process full of questioning many things that are, should or could be different from printed books. (Another post will address why PDF and not some other format for this e-book.)
Here I’ll share some of the topics that we came across while working:

ORIENTATION: portrait or landscape?

By thinking that we are designing a ‘book’ the impulse is always to go with a known book format (portrait), but since the screen is landscape, it’d be useful to follow that format if the e-book is intended to be read on screen.
However, when we read a print book we are always looking at a landscape format from the moment we open the book: the double page. So finally, I decided to go landscape, but as double page to keep the book familiarity and avoid the feel of a PowerPoint presentation.

Should we use COLOR or B&W?

Should we do it full color? We can! So why not?

A full color e-book can be done for the same price and will be more attractive since it’s full of graphics… ok, let’s think about the audience: what if the people want to actually print it and take it with them? Remember this is a tourist guide!
WHAT TO DO? We decided to work on 2 versions: a screen version with images & full color for people to enjoy, read and look at while planning the trip; and a print version that is B&W with a simpler layout. So by printing 11 letter-size pages of the print version then the reader can have the complete text to go.
Here an example of the screen version and the print version:

One complicated part we encountered was a double page with an architectural walking tour that included buildings photos: in this case we just left the map in the print version with references (so people could find the buidings) without images and included the text of that section:

To keep the feel of the book, the print version has the same text orientation (landscape), so by slightly modifying the original grid it was ready:

TYPOGRAPHY: screen font or book font?

I wanted a font family that could be used for the whole project, including the print version. The Rotis family was the choice because of the maximum readability and many options to combine the different levels of hierarchies of headings and text. The main text is set in Rotis Sans Serif and the headings are Rotis Serif & Rotis Semi Serif.

With or without LINKS?

I find it useful when a multi-page document (e-book in this case) has anchors from the Table of Contents linking to the corresponding pages in the e-book. Also since this is an e-book all Web sites mentioned in the e-book are actual links embedded in the document.

COVER

To be consistent with the landscape look of the whole project, the cover was done in the same style, so when opening the document all the pages are the same size, including the cover.