With granite, you have the opportunity to have an undermount sink. Most folks go with stainless or one of the new composites, like Silgranite. I think the Silgranite could work for you.

There are many options. The most common are:

1. Enamelled cast iron. Indestructible. Kohler makes the best quality. They've changed from the old porcelain to a harder enamel that fires much hotter. It's almost impossible to chip or stain. They demonstrate it by throwing cast iron frying pans at it. (Don't do this until it's installed. You can actually crack the iron when it isn't braced. Rare, but it happens) Comes in all kinds of sizes, shapes and colors.

2. Old fashioned porcelain on cast iron. Limited choices, mostly in classic or reproduction shapes. Can be stained, though usually can be cleaned or bleached. Can be cracked or chipped, though rarely. Pretty darned durable. You can also get these at salvage yards where 100 year old ones are still lovely.

3. Fireclay. All the clay without the iron. Pretty much hand made. Feels wonderful. Looks gorgeous. A little more prone to cracking and chipping than the above, but more durable than vitreous china (think bathroom fixtures). The apron of farm sinks is particularly vulnerable. Hard to stain. Don't over tighten the drain/disposer flange, as the pressure can cause cracking. Do wait to make the opening for it until you have the actual sink because there there is size variation, unlike molded or manufactured sinks. Also, order early because these are more likely to be damaged in shipping than other sinks. Really gorgeous though.

4. Stainless. Different sizes, shapes, thicknesses, and finishes. A polished finish is hard to keep polished looking. Do scratch, but build up an overall patina where scratches don't show. Can be made "zero radius" where the corners are perfectly 90 degres...which is also harder to clean. Many options for placement of the drain. Highly durable, though can be dented and scratched.

5. Other metals such as brass or copper. Brass is only really appropriate for a little used bar sink. Hard to maintain. Copper is said to be naturally antimicrobial, which is great. It has a living finish, however, which means that any acids (tomato, lemon, vinegar) will bring out the "new penny" copper color, where the rest will oxidize and go dark. A splatter can look like freckles until it darkens, etc. If you love the look, a great choice. If you don't, skip it. Many shapes, sizes and colors, plus custom, can be dented and scratched, very durable other than finish.

6. Granite dust molded in resin. E.g., Silgranite. Warm to the touch. Slightly textured. Easy to clean. Durable. Some selection of styles and colors. Matte finish (non-reflective).

7. Natural stone. Sinks can be carved out of a chunk of soapstone, marble or other carvable stone. Heavy. Expensive. Exceedingly durable. May stain if made of marble or other porous stone. There are some stain cures, but they're a bother. Does age and develop patina. It's a hollowed out rock. :)

8. Natural stone contruction: Straight sided sinks are also made out of slabs of stone. Soapstone, granite and others. These are assembled. Theoretically, could develop leaks at the joins, but that doesn't seem to happen enough for word to get around. Will develop patina according to the stone type, but easy care and quite durable. Small (very small) potential for cracking crystalline stone. Heavy, but not as heavy as solid stone. Possibility of staining according to specific stone. Can be customized to location and purpose. Hard to clean the cracks where the slabs meet.

9. Corian and other plastics. Can be integrated into countertop. Light weight. "Soft" on breakables. Easy to scratch and stain. Can be, by repute, refinished with sandpaper.

10. Glass. Easy to clean. Not porous. Easy to crack. Doesn't like thermal shock. Looks amazing.

We are doing exactly what you're doing, counters and sink only. I have only had enamel over cast iron in my last 3 houses (which is very durable and easy to keep clean), but I have been looking at stainless and fireclay to see what the differences are. I say to go out to a plumbing supply store and just see what's out there. Ask the salespeople about the different materials, then ask a plumber (surprisingly, I was more knowledgeable than the sweet sales girl at my store. I have GW to thank for that!). I had never seen a fireclay sink in person until last Tuesday. Smooth and gorgeous! Franke Orca in stainless? *drool*

Have fun! Enjoy the process!

I am having my plumber spec out the prices of the top three of my likes. I wouldn't be doing this with him, though, if I hadn't done the touch-y feel-y test at the store.