@Ath:
I'm sorry, I hadn't seen the edit on your post with your experiments... I've loaded it onto the iLiad to test them out.
The first one, apart from the ragged look (which I'm not too fond of, but that's something else), is too close together, the font is rather high, and there's not enough interline spacing for reading comfort. The second and third are great, I can't see much difference between them, but both are very readable and nicely set out. The fourth has too much space, as you said. The fifth (small font) IS readable on the iLiad without problems (unless you have bad eyesight, I don't), but the small font makes the lines too long unless you increase the side margins, methinks.
Having looked at Georgia, I went back to Century, because I don't like the way Georgia eats up the space between lines. I didn't get further than the g's on my font list though, so I might find something decent like Palatino further on. Right now, I have a conflict of interests, LOL, since I can either actually read a book, or prepare it. I'm taking turns.