chicago's plazas

Alright, a couple of questions on chicago's urban plaza's:

Which ones are the greatest for architecture and bringing people in? which one is the best overall (combining architecture and bringing people in)? which is the worst for the same two questions I just asked? also, do you think that the plaza was a success or failure for chicago? Finally, how do you think chicago's plazas compare with the rest of urban america?

just curious, i personally think the negativity of plaza outweigh the benefits, however some plazas do it well. also, can you think of any new skyscrapers in chicago that are being constructed/proposed with plazas?