Freight by Joshua Darden comes to the top of my mind:
http://joshuadarden.com/
&
http://www.philsfonts.com/sresults.html?key=4&fcs=freight052005

Agfa Rotis
http://www.fonts.com/findfonts/detail.htm?pid=421585
ITC Officina
http://www.itcfonts.com/fonts/detail.htm?pid=414187
Base Nine and Twelve™ from Emigre
http://www.myfonts.com/fonts/emigre/base-9-and-12/
Versa and Fresco from OurType
http://www.ourtype.be/
Mentor
http://www.monotypefonts.com/WhatsNew/Releases.asp?show=mentor
Nexus and Scala from FontFont
http://www.fontfont.com
Alinea & Placebo from Présence Typo
http://www.presencetypo.com

Marvellous 'John Baskerville' and 'John Sans', by František Štorm
'Dederon Serif' and 'Dederon Sans', by Tomáš Brousil

Dav

* Yea, I DO love Czech Type :)

>> I DO love Czech Type
Peter Biľak's
Fedra
http://www.typotheque.com/site/fonts.php?id=6

and Eureka

Panoptica is the champ, with seven different typeface styles.

Fontesque has Display and Text versions of the serif styles, five weights of sans, and four styles of ornament.

Scala
Quadraat
Fedra and Eureka (Typotheque)
Clearface
Legacy

***

Gill Sans/Perpetua
Avant Garde/Lubalin Graph
Optima/Palatino

Many of Gerard Unger's designs have a commonality of proportion, so his sans faces would work well with serif, and this is probably true of quite a few other designers' work.

Seria/Seria Sans

Other than creating an artificial rush of "suggestions" the question I have is: why?

Let's see.

FF Absara...
Psy/Ops used to sell Eidetic Modern & Eidetic Serif...
Neutra, Gotham, Paperback, Farnham, Mercury...

Lots more...

--Michael.

------------------------------------------------------
// love what you do or do something else. //
Michael Ebert -- graphic designer, jazz saxophonist, horror movie devotee
http://homepage.mac.com/mwebert
mwebert@mac.com
--------------

thanks for all the suggestions!

>> Other than creating an artificial rush of “suggestions” the question I have is: why?

im doing an internship right now and for a clients new CD a co-worker was compiling a list of large font families, because for bigger clients, it is very handy (and probably easier to convince the client to buy it) if you have one family that includes sans and serif .

grrrr. double post. Anyone else having problems with the site lately?

double posts? cant see any doubleposts in this thread.

It was my double post - I edited it. I am finding this site grindingly slow lately and keep getting timed out while I try to post.

anymore?

...why?

Convenience.

However, that is only part of the reason that sans + serif families exist, and not the main reason.

They exist for the expediency of the type designer/foundry, not because having a sans + serif family is necessarily a good idea for the end user.

I extended the Fontesque family to include sans, not because I envisioned typographers mixing the two in layouts, but because the original serif face had proven to be a popular type design, and brand, so a product extension seemed like a good bet.

Also, once the type designer has one version of the face, it's a big time saver to use its outlines and metrics to construct the other.

Of course, typographers can use a mega-family sans + serif in the same layouts to good effect, but speaking from under my art director hat, I think it's much more interesting to see someone artfully match a pair of typefaces that no-one else has previously teamed up.

Using sans + serif from the same mega-family is in danger of being rather obvious, and may even be just plain lazy.

James Montalbano, among others, has a better idea -- matched typefaces (Alfon and Giacomo) designed to work together, but with sufficient stylistic contrast to be piquant.

The main thing is to give them the same vertical metrics, and similar horizontal proportions.

Sans and serif suites.