Pianoteq and Ivory are the top choices IMHO.
 
If you like to tinker with the sound, Pianoteq is the one for you as just about every nuance of the sound can easily be changed.
It's also comparatively light on CPU and resources.
 
Ivory II is very demanding on resources especially when running full steam with all voices etc.
I like the Yamaha (included in the Grand Pianos package) and the Italian Grand.
With a good weighted controller, both play and sound very realistic.

carl
Sampletekk
http://www.sampletekk.com
Ivory
http://www.synthogy.com/products/ivorygrand.html
 Xln addictive keys
http://www.xlnaudio.com/productline/2
 

+1 what Carl said. I own a Sampletekk 7CG and Ivory II. Both have wonderful piano sounds. Very playable too.
 
Regards,
Dan

Also notice that Sampletekk has started the Summer Sale
http://www.sampletekk.com/

It is interesting how these massive sound libraries have changed our perceptions.  If you visit various schools, churches, auditoriums, and homes and play the pianos you find, I will bet no two of them sound alike; and that almost none of them will sound nearly as good as what we expect from our VIs.  The quality of the real pianos will vary widely and few of them will live in acoustic environments as pristine as those used to record the top libraries.  I have a good quality and well-reviewed digital piano in my living room (for non-studio stuff) and I don't like the way it sounds compared to Ivory; however, not long ago I was thrilled by the humble piano in the Roland Sound Canvas.
 
My point is that I love Ivory II, I know EastWest has a good product, etc.; but if I had nothing but the free piano bundled with Sonar or had to go back to one of my external MIDI keyboards, life would go on.

Ivory II is a lot better than Ivory I and PianoTeq 4 is light years ahead of PianoTeq 3.
Just my opinion.
 
 
 

Ahh but Sampletekk needs Kontakt - might be a deal-breaker for some. ALL dimension pro (even the add-on libraries) pianos suck!! EP's included.
 
A.A.S. or G.S.I. EP's are the best - True P's Atlantis and Diamond modules are pretty good (the ones I currently have) but all the TP modules seem to suffer a "honkyness"  around C3 - C4 YMMV.
 
I am also looking for a new Acoustic Piano, that does NOT need Kontakt, nor a dongle...and is a reasonable price - ie under $200.
 
 

http://www.sweetwater.com/store/search.php?s=ivory+ii&Go=Search
 
Ivory II Grands is over $300 BUT includes three pianos.  You can get Ivory American D (Steinway) for well under $200 and it has received excellent reviews.  The way it is voiced, the single Steinway may be all you ever need.  Sound on Sound gave it a rave review.  Warning:  I think you will need an iLok for Ivory.  That has not been a problem for me but many people don't like it and it is an extra $30-40.  With the iLok you might be $20 over your budget but you will own a sampled piano that is as good as anything out there.

joden
Ahh but Sampletekk needs Kontakt - might be a deal-breaker for some. ALL dimension pro (even the add-on libraries) pianos suck!! EP's included.
 
A.A.S. or G.S.I. EP's are the best - True P's Atlantis and Diamond modules are pretty good (the ones I currently have) but all the TP modules seem to suffer a "honkyness"  around C3 - C4 YMMV.
 
I am also looking for a new Acoustic Piano, that does NOT need Kontakt, nor a dongle...and is a reasonable price - ie under $200.
 
 

I'd check out Eighty Eight 2.0 from Sonivox.  I think the current 50% sale puts it at $75.   I'm in the same boat - I don't own Kontakt, I don't want a dongle, and I also have no internet connection on my DAW (XLN).   Oh, and I'm not even in the < $200 range.  
 
 

joden
Ahh but Sampletekk needs Kontakt - might be a deal-breaker for some.

Not the Black. http://www.sampletekk.com/proddetail.php?prod=STDELIVER-039-KONT
 
This runs in the free Kontakt player. Its $50 in the current sale, which is exceptional value. This is now my go-to grand piano. It also has more control than the others, e.g. variable sympathetic resonance.
 
Out of the other (full Kontakt required) Sampletekk pianos I particularly like Old lady, Emperor and Estonia. Estonia is far from being the most detailed library but it just has a wonderful tone.
 
I absolutely concur with those that say True Pianos "Amber" is not as good as the other pianos in the full version. I like "Atlantis" best, followed by Diamond.

I found Scarbee ALICIA'S KEYS absolutely perfect for me. Very tweakable and cheap...