Text: For the most basic use reg, italic and bold is fine. A really complicated editorial task might need medium or semibold+italics (or even better, a smaller optical size) and at times also a bold italic. But is DIN a text face? And how dark do you want your "regular" to be?

Display: Anything goes, but the zeitgeist seems to be high contrasts: very dark vs. very light, thick vs. thin, or ornateed/untypical details: and in the case of DIN, perhaps the rounded version. Editorial work is much more convenient with a condensed and a compressed version.

Disclaimer: This all depends on the kind of work you want to do.

Thanks! I was wondering though: if you're using a Regular weight for your copy, when you bold that, do you use Medium (if there is one) or Bold as defined by the foundry?

The same goes for if you were using Light: do you “bold” it with Regular, or with Medium, or with Bold?

Or is it up to the setter?

I guess why I'm asking is, in the case of DIN, should I get regular, bold (skipping medium), and italic? or medium, bold, and medium italic?

This depends on the typeface, as some faces have more weights than others. Pick a bold that have enough contrast.

Carl,

You can see also Palestina at www.tipo.net.ar or http://new.myfonts.com/fonts/tipo/palestina/

Good luck!
Eduarrdo Tunni