Hi Dan...
Maybe i'm wrong but, take care: i think "shiramasen" is not correct > "shirimasen/ しりません / 知りません (polite)" or "shirunai/ しるない / 知るない(neutral)" might be the good one but my level is not high enough to be sure.
My favorite word is maybe: "Sakana / さかな / 魚" which means "Fish"...
There are a number of Japanese words that sound rather beautiful when spoken. A lot of my favourites come from my martial arts experience as some kata names just roll off the tongue so well (e.g. zantotsuto, urokogaeshi, zenteki gyaku to) and some have a profound meaning, particularly Kaishaku.
Mines is KY or Kuuki yomenai (空気読めない)
I learned this through a friend's friend, and it means that you can't read the atmosphere.
tatoeba, if someone says something offensive and they don't realize it you can say that, or
in similar situations where one person is just unaware of the tensions.