You haven't said what part of the world you're in -
A previous post situates the OP an hour outside New York.
I've played three Steinway grands from different periods and to my ears I felt that they didn't sound as good as my U3 upright.
I have a little knowledge of what a good tone is, played saxophone for many years but is it possible that I don't know what a good piano tone is?
I'm stuck on the Steinway.
So, to reiterate:
You despartly want a smaller, NY Steinway grand for some reason, but you failed to find one you liked better than your Yamaha U3. Is that strange?
Taste is I subjective, and the smallest Steinway is small. Unless you give more details, the quality, production date, and price point, is all unknown to us.
When we, as in many of the piano buyers on this forum, evaluate a (grand) piano, the following criteria, at the top of my head, are often reflected upon (some overlap):
Sound (per register)
Suitability for repertoire
Touch and response
Control of dynamics
History of manufacturer
All these criteria have a scale that we depending on our references evaluate against. These references can be other pianos we have played, performances we have heard, marketing, forums... and as such may or may not be relevant. Marketing is all about creating these references, so that we become confident in our buying decisions.
I have an acquaintance with a reasonable economy. He has a piano at home that in my opinion, fails on everything but price. You can hit it with a sledgehammer, but all you will ever get out is a mp. He likes it however, because that way he can play without disturbing anyone. His only criteria was sentimental value and lack of dynamics.to others these would count the other way around.
The piano that wins for us, is the one that scores the highest on our criteria list. The criteria have a threshold. Let us say you have a threshold for price at $20.100. It does not matter how good it is, you simply cannot buy; now. The now is important, because in one year from now, your price threshold might be $29.000. So all or most of the criteria may change threshold over time.
As I read you, the three Steinways you tried failed on your sound criterion, but passed other thresholds you might have had. This could sound odd if they had all beeen new grands, but apparently they were not.
I recall an interview with a Steinway artist, describing Steinway pianos as the best in the world (why not the universe while we are at it). The interviewer then quite cleverly followed up with which other brands he had played... and it turned out to be 2... some people do not hear the difference between two Steinways, and some people do not here the difference between two pianos of different brands.
I think if you want useful input, it helps to be a specific as possible on the criteria you value and why. List as much details as possible about the pianos you evaluate to prevent guesswork.
In order to develop a good understanding of good tone, you should go to as many piano venues as possible, with as many different pianos as you can find. It is time consuming to make a good buy, Do not rush it.