Well, it all depends on your friend's preferences, I'd say! If you want something for warmth, 100% silk might not be the best, though it'd be beautiful!
Malabrigo has some fans on here, I know.
Worsted would make for a quick knit, but lighter weight yarns in a lacy pattern would be very impressive. Knitting Pattern Central has lots of free shawl patterns
you can peruse. Cozy and Clapotis on www.knitty.com
are very popular and not too difficult patterns.