Times Roman, Caledonia, Electra and Palatino would be my choice

Can you give us any details about what sort of books you’re creating?
It would help, as there are many amazing ones out there. Personally, I think Lexicon and Trinité are two of the absolutely best, but they cost a lot of money. I hope some day I’ll land a job that’ll let me license one of them.

pretty much every other book I've ever read is set in adobe caslon.

frode frank: We're creating text driven non fiction books. Trim size: 5 x 8 and 6 x 9.

Lexicon looks nice.

What theme?

Can you post a photo of the Garamond typesetting? They must be setting it wrong if it doesn't read well. I would consider it a workhorse -- it has small caps, oldstyle numerals, fractions, etc. And we've all read it so often that the reader isn't distracted by the face itself.

On the other hand, the full features of this typeface is simply amazing:
http://www.houseind.com/fonts/eames

In Germany the most common textface for books is Stempel Garamond.

In Brazil the most common fonts in books are Times New Roman, Adobe Garamond, Minion, Palatino, Berthold Garamond and Caslon. And Arial/Helvetica is largely used too (!).

Anyway, I don't think these choices are based on readability or flexibility of use. I'm sure there is very much about tradition and typographical ignorance in many book design made here.

There are many good font options nowadays.

For a non fiction, technical book, I'd definitively avoid Garamond (all flavors) and also other Garaldes and Venetians. I'd favors some contemporary fonts like Novel, Athelas, Lyon, Calluna or Romulus. If the text is not continuous (I mean, if it mix graphics, tables, equations and so on) other choices could be Tiempos, Expo Pro, Documenta, Stuart, Skolar or Karmina.

If there is heavy numeric usage, pay special attention to the figures. Although the traditional old style numbers are very elegant, they are far from good to a text with many numbers.

Minion, Palatino, New Century Schoolbook, Times New Roman and Legacy are the ones i see most often. With a bit of Charter and Elzevir mixed in.

and i get real happy when i see Chaparral and Arno get used

Adobe Caslon also works well.

Are you more interested in "what most publishers use" or "readability"?

For readability, take a look at Janson Text.

"In the 1930s, Janson Text replaced Caslon as the face of choice for fine bookmaking. Its strong design and clear stroke contrast combine to create text that is both elegant and easy to read."

I know I'm at minority side on this, but I think that non-fiction texts are much better set with more contemporary fonts. Caslon and Janson are out of my choice, they produce a very classy but outdated effect to technical texts.

I’m with you on the minority side Igor, but he won’t get better suggestions unless he reveals more details.

Something contemporary, like Maiola, Loreto, Collis, FF Tisa or Cycles.

Although not all of them do not have all the cuts which might be needed. Have a look and talk with your publisher.