Here's my short list:

Seeing Birgit Nilsson at the old Met in "Die Walkuere" and "Tristan und Isolde" at the new Met
Watching birds flying around on top of the Jungfraujoch, above the glacier and in almost perfect silence
Riding the cog railway from Ootacamund to Mettupalalvan, partially in the (steam) engine
Hearing the Berlin Philharmonic with Herbert von Karajan at Carnegie Hall play Brahms' Third Symphony
Landing at Kai Tak airport in Hong Kong early one morning, with the islands in the bay still covered in mist
Riding the "Blue Train" from Capetown to Johannesburg in a cabin with private bath and bathtub
Eating grilled Lake Baikal fish bought from peddlers on the Irkutsk station platform
Taking my first trip alone across the Atlantic as a teenager on an ocean liner and passing icebergs off Cape Race
Eating an absolutely wonderful tripe dish after years of hating the version my mother made
Eating my mother's Swabian food
Seeing Prague for the first time (1967)
Discovering Mozart's late symphonies (much too late in my life)
Finishing Proust's "In Remembrance of Things Past" over drinks in the lounge of the dome observation car on the "Sunset Ltd." in the middle of Texas as the sun set

This is too much; I'll stop here!