Ignoring FFX-2 for a second...

If you return to Macalania Temple after getting the Airship and talk to the fayth of Shiva, she says that they'll reward Tidus for his sacrifice by creating an everlasting dream for him - one where he can swim free in the ocean. So in FFX's 'final ending', it's like he's entered his own personal heaven, courtesy of the dying wish of all the fayth.