Critical statements made about the concept of Paradise in relation to Middle-earth have all been rather straight-forward: the Undying Lands are it.
Within the basic definitions of Tolkien's mythology, Frodo's destination is known as the Undying Lands (or Aman).
Because they have been cut off as a result of men's actions, after the Second Age the Undying Lands become a place between Over-heaven and Middle-earth, a place accessed from the lower realm only by special appointment, we might say, for it was only by the leave and assistance of the Valar that one could make the crossing.
But still the question remains of how we are to understand such a place in our own worldview, and whether or not the Undying Lands are in fact paradise for humanity.
(Letters 328) The name "Undying Lands" is a misnomer as far as mortals go, it seems, and the men of Numenor were misled indeed when they thought that to live there meant immortality.