I readily admit to being an "old style" cacher. Whilst I admire - to some extent - the increase in "cerebral" caches that require considerable brain power; they're not generally my scene.
The "special" cache that sold me on Geocaching was one placed near the Roman Villa at Witcombe, Glos. It is such a lovely spot and I now have a cache there, (the original has gone!); however, I just love going there and being there.
As for special cache locations - then I would have to say the Snowdonia area, where I have done some really memorable caching!