Bob's is, to the best of my knowledge, the biggest motorcycle boneyard in the US. The yard in Rye was pretty big too, but the owner was a hoarder and not interested in selling things. There is a great yard in Albuquerque, NM as well. I believe there is another yard or two in Tucson, but I haven't seen it/them. And there were one or two smaller yards in the Phoenix area as well.
And yes, the aviation boneyards are pretty crazy, but as far as I know you can't get close to the airliner boneyard -- it's pretty well guarded and high security. The Pima Air Museum in Tucson, however, is amazing and you can get up close to planes that go back to the beginning of aviation. Lots of WWII warbirds, and docents who flew/worked on them (although obviously their number is sadly decreasing).
No humidity and very little rain makes Arizona ideal. What we lose, however, are side covers and other plastic, and wiring can become brittle and prone to shorts. Still, there is still plenty of original chrome that's in great shape. And there is plenty of cheap space available.
I work mostly on Hondas, so I know those areas in Bob's pretty well. When I work on a Yamaha or Suzuki and need something it's exploring unfamiliar territory, but it's a blast. And there's so much stuff there that I imagine there are some amazing period goodies in there hiding inside cases and under piles.
