First you'll need to get to where you're going. Jim Cosgrove is offering up a free download of his song "Gobble Across the USA" here (enter "gobble" as the checkout code). As Cosgrove notes, it's not really a Thanksgiving song, but it features a lot of gobbling and a lot of food, which seems appropriate enough for me.
Then, once you get there, the prayer, courtesy of Bill Harley. His poem is called "Thanksgiving Prayer" and regardless of your religious affiliation (or lack thereof), I think you'll appreciate it.
[And here's a second blessing of sorts, this one coming from the Harmonica Pocket -- it's called "Give Thanks" and you can download it here.]