We have a stainless sink and I would not have one again because they are thin. When we use the garbage disposal the sink rattles and allows the cvp pipes to move. Over time they look bad and mine looks dirty no matter how much or what I use to clean it.
We're redoing our kitchen and we're able to do granite counter tops with a granite sink, it's been a long wait for me.

Tateland, if you do a search in the bottom search box, you'll see that this has been discussed a lot! That being said, here's what I learned during my research:

Thickness or gauge  The lower the gauge, the thicker the steel. Average home sink is 21 gauge. Good quality is 18 gauge. High end is 16 gauge. Less than 18 may leave sink vulnerable to dents.

Chromium  Type 304 stainless has extra chromium and is less susceptible to corrosion.

Nickel - 18:10 or 18:8 nickel/stainless steel ratio for pro quality.

Noise  An undercoating further muffles sound. Without sound-reduction measures, a metal sink can act like a giant bell that amplifies the clang of every fork dropped into it.

Surface  Satin finish is more durable, doesnÂt show marks and scratches as readily.

Consumer Reports - Says gauge doesn't matter! Tested 18 to 23 gauge sinks. Listened to the noise made by running water and dropped weights. All resisted dents, stains, scratches, and heat, and silenced noise similarly.

When I was researching Ticor sinks, they met all of the above requirements and I was sold. I ended up getting a Silgrant sink, but it had more to do with size constraints than anything else.

My two Ticor sinks which are almost a year old still look new. They are very quite, and for the money I don't think you can get a better sink. Even my GC is now putting them in all of his homes now instead of Kohler.
I would try to go with at least 18 gauge and make sure the sink has an undercoat or sound pads.

Our SS sink in our old kitchen, while builder-grade, wore fine. It did develop a patina over the nearly 13 years we had it but it never looked dirty unless it actually was! (My parents' old porcelain covered cast iron sink, OTOH, did stain and over time always look dirty! They switched to SS and never looked back! And my mother is one who prefers "vintage" to modern/contemporary.)

Our new kitchen as 2 SS sinks...one is a Ticor, the other Kohler. We've been using them for over 9 months now and I've not noticed any rattling (even when the GD is running) or any movement of the water pipes. They both look like new! I admit, though, that I do have grids in both sinks so that may be cutting down on the scratching...it just means it will take longer for the "patina" to develop. Neither sink looks "dirty" if it isn't actually dirty.

This is the first time I've heard anything about pipes moving when the GD is running...perhaps it's an installation problem rather than a material problem?

As to looking "dirty"...I've never heard that either...is it possible that at one time someone used a harsh chemical on the sink that destroyed the finish?

When we were considering different countertop\sink options I found that you don't encounter many undermounts under 18 guage - which I took as a reccomendation not to go lower than an 18 with an undermount. We ended up doing a drop-in that's 20 guage (very common guage for a drop-in) and it doesn't flex at all. You might give some thought to drain placement (rear is often preferred to maximize the use of the cupboard beneath). I have read that 302 stainless is more desirable but you don't see many manufacturers using it.

We love our Julien 16 gauge sink (0-radius; 30X17X10). It had an initial drainage issue that seemed to correct itself (settling?)--we've been very happy with it ever since. I'd get another one in a heartbeat.