(EDIT:  To all concerned, please do not take the above comments as a condemnation of Steinway piano products.  They are highly valued musical instruments.  The "variability" I notice is found mainly in the final voicing of the instruments; I do NOT intimate that Steinways are poor pianos by any means and there is nothing materially wrong or defective about a new Steinway piano as it leaves the factory, barring unforeseen damage during shipping.  Apparently, I hold some of the world's finest pianos to a higher standard of voicing, sensitivity, repetition and general touch ... BECAUSE of their excellent pedigree, I am expecting them to be tuned and voiced in concert-ready condition.
End Edit)

That said, ...
Some of the finest pianos -- and some of the worst pianos I have played -- have been Steinways.  At their best, a Steinway Model M (5'7") can be a glorious instrument to play, especially in a domestic/home studio environment.  If you are going to be doing any professional recording with the instrument, then the very least length of Steinway should be a Model B (nominally 7' in overall length). 

If you are looking into purchasing a rebuilt/refurbished Steinway, then only do it from a reputable dealer and pay the extra money they will inevitably charge.  Hint:  NEVER purchase ANY grand piano whose inside rim is lined with what looks like thick rope.  Such a feature is an indication that the soundboard has been replaced, and it doesn't fit quite right, hence the "rope" used to cover all of the uneven overlap of replaced soundboard in a given case.

Also, if looking into purchasing a used/rebuilt/refurbished Steinway or other fine piano, please look at the large screwheads holding the cast iron frame to the case.  IF you find "messed-up" screw heads, such as damaged screwheads -- then RUN, don't walk away from the deal.  This is an indication of a possibly shoddy job of handling the piano during the rebuild/refurbish process.

Regarding a Steinway piano's estimated age, take note of the serial number cast into the frame, and compare it to the year of manufacture via the internet.  Often times, a "20 year old" Steinway is in fact an "80 year old" Steinway.

I have said nothing regarding the physical condition of the felt hammers; that's a volume unto itself.

If you find that a given Steinway has real ivory keys (meaning that the key surfaces have horizontal splits in them, in order to save on ivory), just beware that such a piano was manufactured BEFORE about 1950.  Stated a different way, a 30 year old Steinway in original condition will NOT have ivory keys!

Enough of my rambling,

Cheers,

Joe

If you like to gaze at a grand piano as a piece of furniture, by all means they are fine for apartments.  If you don't like to look at a grand piano, an upright sounds great, and has few differences (note repetition speed is usually quoted, but my too-stiff return springs that I put into my upright by mistake have given me pretty-darn quick repetition), and fits in a much smaller space.  Also, uprights are much cheaper - I paid $2000 for my already-rebuilt 1885 Steinway "F" upright from a Craigslist post.

If money is no object, she should buy the Steinway of her dreams and get a QRS PNOscan MIDI rail and Stop rail installed - some dealers sell all of their new pianos that way.  Or even with a full player setup, if that's her goal.

If money is some object, and she doesn't want used, the Yamaha TransAcoustic series is really nice, allowing both for out-of-the-box MIDI along with the clean sound of an acoustic Yamaha baby grand or upright.  Such a device has a stop rail which makes it easy in an apartment to play with headphones.

If money is some object, and she doesn't want to mess with piano tuners and out-of tune notes, and she can tolerate an all-electronic performance, the Yamaha AvantGrand series is quite good.

If money is an object, and she doesn't mind a little effort (or paid effort), have her pick the used piano of her dreams and install the QRS PNOscan MIDI strip and a stop rail - used pianos are a bargain compared to new pianos.  Clearwater, Florida (for example) has a store called Randy's Piano Warehouse - under one roof, I walked up and down the aisles testing Steinways, Mason-Hamlins, a Boesendorfer, Baldwins, Webers, a couple of Apollos ($3K for a nice turn-of-the-prior-century Apollo baby grand with fabulous bass), Yamahas, and so forth.  It's a great way to 'kick the tires', if nothing else, even if she doesn't buy from such a place.  And then again, she might find just what she wants.

Just as when you are looking for a loyal companion dog as a pet, there are all too many homeless pianos that are looking to be adopted by an adoring human.

One of my friend is looking to purchase a new Steinway grand piano, she is a pretty advanced classical player (playing Bach Prelude and Fugues, Beethoven Sonatas, Chopin Walzes...etc.). Given the fact that she lives in an ~700 square feet apartment, she is looking at the smaller ones (Model S or Model M). I have really no experience in playing a Steinway (except for the Pianoteq Steinway Model D and Model B of course! ) so I would like to seek advice for the following:

1. Anyone has experiences with playing the smaller models (Model S or Model M) of Steinway Grand? How was the experience? Are they worth the significant cost? Are small Steinways just Steinways in name but a very different piano altogether compared to their bigger models?
2. Are grand pianos in general a good idea for an apartment setting? What is the chance of overwhelming volume contributing to a negative experience to the piano player him/herself and annoying the neighbors at the same time?
3. If you were my friend, and if cost is not a factor (but everything else is, including the living conditions), would you purchase a Steinway "baby" grand or purchase a top of the line hybrid piano (e.g., Yamaha Avantgrand or Kawai Novus) and run Pianoteq?

Any ideas / opinions / experiences will be greatly appreciated.