This is a great thread and in thinking about it I realize how much has to do with when I visited.
The first time I visited NYC, we stayed at the Trump and had a view of Central Park. At the time, that was the best for me, though now I would never stay at Colombus Circle.
The first time I visited anywhere in Asia, we stayed at the Regent in Hong Kong. Staring at the harbor was amazing, though again now when I go to HK, I only stay on the island (Upper House or FS).
My next truly stunning location was probably at the Splendido in Portofino.
The first time my (now) wife and I went to Paris, we were upgraded to suite# 887/888 at the Plaza Athenee, truly special.
Our first Aman was Amanjiwo and was amazing, but purely in terms of location of the property I would probably prefer Amandari / Amanoi
Also, I think almost any top safari could be mentioned here, but having only been two three camps, I will list: Serengeti Bushtops, &Beyond Tree top and &beyond ngorongoro crater lodge (though this one had the worst game viewing experience).