Ok, I've got some more possibilities to add to the "bucket list"
Necropolis of Britannai Manor III http://coord.info/gc2b034
See this Latitude 47 post: http://blog.geocaching.com/2010/08/r...deo/trackback/
Rainbow Hydrothermal Vents http://coord.info/gcg822
International Space Station http://coord.info/gc1be91
Those last two I have in another database named "Notable Caches". I put caches in there that'd be neat to find, but most likely would never even considering attempting.
Interesting thread and really cool posting by the members.