Here's MHO, FWIW.

I wholeheartedly think Silgranit would be better than SS. I myself have SS, and am constantly annoyed at the water spots. It is a purchase I regret, but I didn't know about Silgranit at the time I was buying my sink. If you search on this forum for threads about Silgranit, made by Blanco, you'll see how enthusiastic all the Silgranit owners are.

I think Silgranite in the Anthracite color would be better for you than the white. I think the white will be too glaring a contrast with your soapstone, while the Anthracite color will blend better.

As to shape, I prefer rectangular. I think it is an efficient use of space, and the look is timeless. Some people prefer the D-shape, but I am concerned that the curved corners cut into the usable space too much.

You don't mention whether you prefer single or double bowl configuration, but that is really a question of personal style, and how one operates in one's kitchen. I myself am a fan of a single bowl style, especially if your cabinet base is small, cause I want to be sure I can fit large pans in the sink.

I also like sinks with an offset drain, i.e. not in the center. That way you can set dishes down in the sink without covering the drain.

If only you had a larger sink base than 30", cause I'd like to recommend the Blanco Silgranit Super Single in Anthracite #511-651 (pic shows it in white). It can be undermounted or drop-in mounted.

But for a 30" base, I recommend the Blancoprecis Single Bowl Large in Anthracite #513-428.

Thanks for your detailed response. I actually think I'd like the white sink contrast with the black countertop. I don't really like the black sink...
I love your suggestion of the offset drain. I never would have thought of that!
We want single bowl.
Any thoughts on what SS sink? I'm not that concerned about water spots...I grew up with a SS sink and don't remember that every bothering me.

dcindc - I really like my single bowl ss sink. You mentioned sturdy and this one is 16 gauge, so it's supposed to be a little stronger than 18 or 20 (more resistant to dents & scratches). It's made by Linea Aqua and called Vienna. It's outside length is 30" (inside is 28") and it fits in our 30" sink base.

{{!gwi}}

Here is a link that might be useful: Linea Aqua - Vienna

I would highly recommend one of the Franke sinks with the integral edge. With no grids in it, it is a little over 11" deep from the counter top (the actual sink is 10" deep) but with the bottom grid in place, it raises it to a more comfortable 8 1/2" deep, and with the integral shelf grid in place it raises up to 5" below the countertop. The grids for the integral shelf are half the width of the sink, at least in my Orca, so you can have one just on the left or just on the right or both. I hardly ever work without the grids. Of coarse, that is in large part because I don't do a sink load of dishes by hand, almost all go in the DW and I might hand wash a few pieces under running water without filling up the sink.
I don't have a very long reach and I am not very tall, so I worried if the under mount would be too deep and uncomfortable to work in. The extra shelves have helped immensely with that. I will take out the left shelf to prepare fruits and veggies, etc and peel and cut on the left and have a bowl on the raised shelf on the right. Scraps go right down the GD on the left, food into bowl on right, no mess on counters. I keep the grids in place for a comfortable working height all the time and just remove one when needed for some reason.
I don't think I would have liked a sink this deep without them. With them I LOVE my sink. I always have a comfortable working height, but can make the sink extra deep in a second when needed.
I was a little sad I couldn't get the same type of sink in Silgranite, but the outstanding functionality of these won out.
I know the Oceana can be bought with the integral shelf, but be careful, it comes with and without one. They say it needs a 33" base but I know people here have put it into a 30" Its outside dimensions are 30" and I believe the edge around it just sits perfectly on the top of each side of the 30" sink base.
They are expensive but are available at steep discounts. I bought mine at faucetdirect.com, and they are available on Ebay. Call if you are interested in faucetdirect.com, and ask for their best price. They will match or beat any other price you get and will give you a lower phone price if you ask for the lowest price available than they offer on the website.

Sue

I recommend you check out Ticor sinks (SS) at Galaxy Tool Supply. Their prices are very reasonable. I think they also have an eBay store.

Most of their sinks are 16-gauge with sink grids & strainers included. (If they don't include a sink grid they may be C-Tech rather than Ticor.)

One note...even though the strainers came w/the Ticor, I did buy Kohler DuoStrainers to use instead...and they are awesome! The Ticor ones are probably fine and many here have used them, but the DuoStrainers seem much more substantial and, to me, seem better overall (especially the strainers).

HTH!

Here is a link that might be useful: Ticor Undermount Sinks (Galaxy Tool Supply)