Eins--
Enjoyed this discussion immensely. I am 64.
I played as a child, and once again took lessons from about 1990 to 1993. Then for some reason I sort of dropped it. At the time our kids were taking lessons on our black 5'8" grand, so at least we heard piano music in the house. But then for six years or more, the grand stood silent.
Oddly, we kept having it tuned. Perhaps to assure the quality of its silence!

But then I thought, what a waste! So last September I started preparing Christmas music for the season. In about February I started lessons again.
When you people say you are "old" and you are 36, 40, or 50 years of age, you are not really OLD. I'm not either, but certainly older than you.
I had a notion -- wrong, it turns out -- that I could never get speed, and that I was doomed to play slow pieces, or play lively pieces under tempo. Because, you know, hey, I'm "old." I am delighted to tell you in key passages I can attain really remarkable speed. Some of the Chopin waltzes, where the runs are not terribly difficult but where you just HAVE TO really move. One of the keys to speed is to play enough each day so you develop an intuitive instinct for exactly where they keys are. You can stretch and they are there. And to write in fingerings, so you don't keep making the same mistake in the same place. I sometimes line out the fingering provided on the music, and write in my own. For one thing, I probably have larger hands than what the editor envisioned.
One of the respondents mentioned learning entirely on one's own. Well, I don't agree. My piano teacher has helped me so much with technical points. For instance, I didn't know what mordants are, and how they differ from trills. You find a lot of them in Chopin. She teaches me these sorts of points all the time. Also, I had a bad habit of playing notes on the page even if they were tied from a prior measure. Many of these careless habits have responded to her teaching. Also the wheel of fifths for the keys, and the chord structures.
I probably am not a good advisor for you, but -- IMHO -- I suspect you need a good piano teacher, one with a college diploma in music and with a good flair for people. But I suspect you do
not need a GREAT piano teacher. Such as a university professor of performance arts or something, as you were discussing. You likely want to play some beautiful material for personal satisfaction, and you need feedback that you are playing the music well, not just in some half-baked way. You do not need a Horowitz or a Rubenstein for that.
Perhaps when you are further down the road, you could better profit from some very expensive teacher. But hey, if you have plenty of bucks, why not get the best? It all depends on your situation.
To keep your interest, you might consider a mix of fairly simple show tunes along with the classical pieces. Try to stay way from "dry as dust" scale studies. You have to keep your sense of adventure alive! I was into Chopin waltzes until recently, and started to burn out, so I'm taking on a piece by Bach. An adult learner is not like a child, who must complete each piece in a lesson book, and then --robot-like-- move on to the next.
Being able to read music well is a skill that will come with time. Even then, a good teacher is still worth the $$$.
Enjoyed your posting, good luck ! !
