Katlaughing, I should have said "several songs by" (or listed) rather than "anything by" as I do not have anything approaching a complete collection of her work. Perhaps my friends just have very good taste in which of her truly uplifting songs they choose to sing.
I know people who think Gordon Bok is depressing too, though I personally would listen to his grey-suede voice read a phone book; but among others his songs "Turning Toward the Morning" and "Hay Ledge Song" ("If I could give you three things, I would give you these: song, and laughter, and a wooden boat, on the shining seas...") surely qualify as upward looking.
Allister MacGillivray's "Song for the Mira" and "Here's to Time"
KT, do you always perform solo?
And, two of my favorite sources of "new" material: taking a song previously sung by a man (or the reverse, of course, for my male singer friends), and going back to ones we all knew many many years ago, so standard that no one has actually sung them in years. A friend recently started singing, "Home on the Range," and, do you know, it is a beautiful song.