We had the same experience here. I had The Planets on an RCA LP (I'm thinking Eugene Ormandy conducted it...?), and in the mid 80s, Telarc finally came out with a CD version of it that is my go-to version. About five years ago, we went to see The Planets live--the medical school at a major university has its own orchestra and gives free concerts throughout the season, and it was a great experience. The choir was way up in the balcony, so it was kind of eerie to hear the voices floating around the auditorium.
For the Rachmaninoff Piano Concerto #3, I'd had a chance to see Olga Kern perform it a few years ago, but couldn't make it over to that side of the state. (The tickets weren't expensive.) She performed it in a Van Cliburn competition many years ago and won the top prize for her performance, which is here:
What an ethereal (and also eerie) way to experience the haunting voices of the choir, coming up from above, very befitting db
When I saw it, the choir was next to the stage, behind a big door which they would slowly close in order to get the fade-out effect.
I wasn't familiar with this piano concerto, I only "knew" the one featured in that one Marilyn Monroe scene (The Seven Year Itch)
This 3rd one by Rachmaninoff one sounds nice and picturesque, Olga Kern plays it wonderfully!