I have the immense fortune of travelling to Buenos Aires for the first time. I will be attending a wedding, but will also take a few days to do some sight seeing. Guidebooks are wonderful, but I wanted to know what someone who lives there or has worked in BA can recommend from the "urban planning perspective". Any exceptionally designed areas? What about transit? Any great neighborhoods I can "borrow" design cues from? Anything I shouldn't miss out on?