Coming out of my LJ-posting hibernation to answer this!
I have a few favourite words, and they are as follows:
Nonsensical I just think it's a fun way to say "nonsense". I will actively choose to use 'nonsensical' in place of nonsense, and people look at me with funny expressions on their face. The same thing happens when I use 'poetical' in place of 'poetic', too, actually.
Eidolon This is one of my friend's favourite words, too, and I just like the way it sounds. It means "a specter or phantom".
Lackadaisical As if any other single word could adequately capture the overall feel of being 'carelessly lazy'.