Since you want granite, you might look at Blanco Silgranit Vision. Inside measurements are 22 x 15" because of the angled edge. I wish they had just done a straight edge, but it's a nice deep sink and everything fits. I would have liked a little more bottom surface area to hold more dishes while prepping--it seems I always have to put something on the counter because the sink is full of things I want to handwash, but that's the trade-off for a 27" sink base.

http://www.blanco-germany.com/en_us/en_us/sinks/sinkcollections/silgranit_sink_collections/SILGRANIT.html

Thanks. Yes we were looking at Siligranit, recommended by a friend . The pictures of the Vision model at the link you sent looks like it has an edge that's visible in spite of the undermount? Is that the case? How do you feel about the 22" single bowl? Currently we have a standard stainless double bowl sink. Although the overall width of the single bowl is SMALLER than current double sink width, the actual single bowl itself is much larger than one side of a double bowl sink and probably more functional. Just want to make sure we're doing the right thing and won't be sorry :) The 27" sink base allows us to add much more functionality and storage in the base cabinets.

Appreciate the link about installation using HUSH!

The pictures of the Vision model at the link you sent looks like it has an edge that's visible in spite of the undermount?

When you install an undermount sink you must choose a reveal: negative (can't see the edge of the sink because the counter extends past it, neutral (counter and sink edges aligned), or positive (can see the edge of the sink). There are advantages and disadvantages to each.

This sink will fit easily.

I've put 33" sinks into 33" cabinets.

Thanks for link to Elkay. Will check with installer. So a 9.5"deep undermount sink will be approx 10.5" below counter top surface (slate), correct? Quite a bit deeper that our old stainless double bowl sink....

"So a 9.5"deep undermount sink will be approx 10.5" below counter top surface (slate), correct?"

Yes. You can probably get a 27" sink into a 27" cabinet, especially if you run the HUSH front to back instead of side to side. I've got a reply to a thread about this around here somewhere.

The Vision has what's called a chamfored edge--it's beveled. My other choice was a D sink, which I didn't care for. I went from a 36" sink cabinet to a 27". I gained a trash cabinet, which thrilled me! Previous sink was a Kohler double sink of about the same length IIRC. The Vision has plenty of room for washing dishes. I put my dishes into the DW instead of letting them sit in the sink, but If you have a family that's not willing to put their dishes away, it might get annoying to not have free sink space for rinsing something, for instance.

It looks tiny in this photo but it's not really. It's 23 x 17. My other choice for a rectangular sink was the Kohler Riverby. There might be some apron-front sinks that will fit.

Thanks for the photo and further detail. Lovely kitchen. Are those 42" upper cabinets? You're right - in photos the 24" sinks do look small :) What about strainer/wire rack in sink bottom? I'm also interested in cutting boards that fit atop sink as we have so little counter space.