There's one on the north end of the Myrtle Beach area at a course named Farmstead. One of Willard Byrd's last designs, I believe. The 18th hole is a par 6 that tees off in SC and ends up in NC, which is a pretty good gimmick; the hole is 767 from the tips, and 712 from the second set of tees, which are 6566. You can do the math on that for your own distances, but you've got to hit three really good shots to have any sort of wedge in for the 4th. And to make it a bit tougher, it's sort of a cape hole at that. I don't know if all of that makes it a good hole or a bad hole; I can say for certain that I don't find it to be that much fun to play.
As to the general concept being gimmicky, I don't think it should matter, should it? A par 6 shouldn't be any more gimmicky relative to a par 5 than a par 5 is to a par 4, should it? At least not automatically so, anyway.