After Numenor had sunk it was called "Atalantė" which means in Quenia "The downfallen" Very cleverly done! One gets the idea that Tolkien's story is at the origin of the Atlantis legends..
And as for Aman beeing something like Avalon: I think you are right,
Aethelwine, because the westernmost haven on Tol Erėssea is actually called "Avalonnė" !
And Frodo's departure has alway reminded me a bit of the departure of the injured king Arthur in a boat (with Morgan le Fay and 2 other women), supposedly to be healed in Avalon...
Tolkien did not locate the Undying Lands in the western ocean by accident. In many ancient cultures the setting sun was said to point the way to this special place. The ancient Greeks thought that "Elysium" the island of the Blessed lay in the West, past the edge of the ocean.
In Celtic legend there are also enchanted lands in the West . Two legendary Celtic races that influenced Tolkien's ideas of Elves ( the Tuatha de Danaan and the Shide) were said to heve left Ireland for "Tķr na n'Og", an enchanted island to the West.