hm.. imo, if you want to shot with background bokeh, i think fast lens (big aperture e.g : f/1.4 or f/2.8) will do great.
if you want to shot sunset, i prefer wide angle to capture all the view. So Simga 10-20 will do.

fr the event, it depends too, what kind of shot do you want? people (candid), if candid i think go with Canon 100mm f/2.8 if any kind i think 28-135.

I would prefer not to use auto mode. if for nightshot or night scape, i prefer to use Av mode.
And for event in Chinatown, it depends too. if you want to shot moving subject set it to Tv about 1/125 or 1/250. but since it will be held @ night it might kinda difficult.

anyway that's just my opnion for i will do.