What about Silgranite.. Breezy has a nice silgranite prep sink.

Thanks, jakuvall! I actually thought deeper seemed better, but your post makes me question that..of course...Interesting point, though. It's hard for me to visualize how I'll be using it, since I haven't had one. I'll look into the one you mention.
Gwlolo, I don't think there is a silk granite small enough, but I do like those!

I heard my name! I have an 18' prep sink base with a Blanco silgranit Performa prep sink. It's not quite square from to back (grrrrrr), but the widest interior point is 15.5'. It's about 15' deep front to back in the interior and 9' deep. After under mounting in my 1.5' walnut counter, it's a tad deep. Workable, though. It's soooooo easy to take care of, too.

I'll link the specs below.

Here is a link that might be useful: Blanco silgranit Performa bar sink

Thanks, breezygirl! I truly thought their smallest didn't fit in a 18" cabinet. But I was wrong :)
The quest continues...

Go as big as you can in interior dimensions. The interior dimensions of my prep sink are 15-3/4" x 15-3/4" x 7-1/2"D (plus 1-1/8" granite depth = 8-5/8" total depth). I also have a grid that raises the floor of the sink an inch or so...that means that with the grid, my sink is a little over 7-1/2" deep.

While the 15-3/4" dimensions are usually OK, there are times when I wish it were bigger - but maybe that's b/c I have large hands (and very long fingers!) As to depth, I like that I can put a tall pot in the sink or a deep colander. I don't find it too deep at all.

The sink you've found is larger (at least front-to-back) and has a rear drain - both advantages, I think! Unless you can find one bigger, I would go with the Franke.

Buehl- the rgx is over 9" deep- arx depth is like yours

Added- I like to mount a single handle faucet off the corner of sink allows setting pot on counter, swinging faucet over to fill, less lifting.

This post was edited by jakuvall on Fri, Jun 21, 13 at 7:05

Thanks, Buehl! I do think I'll like the shape of this prep sink. And I plan on using a grid in the bottom, too. I am on the short-side, at 5'2", so I'm not sure if the deeper sink will be better or worse?
But I think I'm over-thinking it, as with every other decision in this project :)
jakuvall, I like that idea--mount the faucet towards the corner! My sink is nearly in the middle of my island, so I'm wondering which way I should place the faucet? I've got a 24" speed oven, then 18" prep sink cab, then 18"trash p/o, then 24" drawer stack. The speed oven end is across from fridge, and the range is farther down the run, directly across from the island.
I have this layout pic saved, but the isalnd has been rearranged and shrunk to match what I described above.

On the range side of the sink

I agree that mounting the faucet in the corner will be more useful. We mounted our prep sink faucet in a corner as well and, in our case, it works especially well b/c:

(1) We have seating on the peninsula - so it puts the faucet farther away from someone sitting at the peninsula behind the sink (and so reduces the chances of splashing the seated person)

(2) Corner sinks are usually mounted further back - so it makes it easier to reach the faucet.

Grid...good idea to have a grid to raise the bottom of the sink. It's also nice to be able to drain pasta w/o the backwash of the water into the colander, provides a flat surface instead of a sloping surface for items in the sink, items in the sink (dishes or food) will not block the flow of water down the drain so it's easier to rinse the sink, etc.

About person height vs sink depth...this is one of the times that shorter is better! Deep sinks are actually more of an issue for tall people than short people. Tall people have to reach even further down to get to the bottom of the sink...so shorter is better!

thanks for the visual jakuvall! so helpful!
and thank you, buehl, for the extended explainations. I especially to hear "shorter is better," because that isn't something I hear everyday!!
I'll be sharing this discussion with my contractor on monday morning!