If you're not doing anything on the weekend of Oct 19-20, you should join a group of us on the Talimena drive. It would be a ways from Amarillo, but a couple of us are coming from way up in Minnesota and Wisconsin. Click on the Talimena-All the Details Here located on the bottom of this post.
Also, every 2 years, a bunch of New Beetle/2012+ Beetle people come from all over the country (and even Canada) and have a GTG in Roswell, New Mexico in June, and the Central group goes right through Amarillo.
Then there's the Tail of the Dragon run in the Smoky Mountains of North Carolina. I haven't done that yet, but I'm pushing for 2014. It's held the first weekend every May.