This has confused many people and come u p in a million debates about the nature of dream Zanarkand and how "real" Tidus and Jecht really are.

The general concensus is that the high-five place is the Farplane, which makes perfect sense for Auron and Braska to be there, because they are dead. However, shouldn't Tidus and Jecht just dissapear, since they aren't real?

Somewhere in the game it says that Tidus and Jecht have become somewhat "real" because they spent so much time in Spira. If that is the case, they may have begun to fade, but before they did completely, they went to the Farplane.

As for the very ending, yes that's the waters off of Besaid. And it is pretty much there as an intro to FFX-2.