After reading paperbacks for many years, since switching to my Sony, I have been looking for a nice clean, simple, and compact Times style serif font like you would find in those paperbacks.
When paperback publishers are trying to save money on a printing run, they use a slightly bolder, dense, clean version of of a simple times style font that is designed to remain legible, even at the smaller type sizes they use to save paper.
Times New Roman didn't quite cut it for me for several reasons, so I went looking for a font that would mirror this 'paperback' experience as closely as possible.
I found a basic Times style font amongst the freely distributed fonts on my Linux box called Nimbus, and then kept tweaking on it, modifying it's character spacing, weight, and the outlines of some of the characters.
There are probably more than 50 individual changes that I made to the original Nimbus font, some to single letters, some to the full character set.
I have taken a freely distributed public domain title from feedbooks, and modified it's CSS to embed the custom font I created, so you can preview the results without doing any customizations to your reader. (loading this EPUB will do no changes to your readers fonts, just let you see the custom font in this text so you can check it out on your actual readers screen and see how it looks)
Feedbooks uses several separate style sheets, some for the introductory material, and one for the main body text.
I modified ONLY the CSS for the main stories text, which causes all the introductory text about the author Lewis Carol to remain in Sony's original typeface.
When you get to the actual main text of the story (which uses the 'body' CSS tag) you will see it in my custom 'NimbusMod' typeface.
FOR COMPARISON PURPOSES, THE "About Carrol" SECTION IS STILL IN SONY'S ORIGINAL FONT.
ONLY THE MAIN TEXT OF THE ACTUAL STORY IS IN MY NEW CUSTOM 'NimbusMod' FONT.
Through the Looking Glass (Story Text In NimbusMod font).epub
Check it out and let me know how it looks on your Sony. On mine, I think that the difference in readability, especially at the smaller font sizes, is pretty dramatic.