c'mon, no-riding-on-the-sidewalk ordinances are almost never enforced by cops. they have better things to do. bike cops ride the sidwewalks. ride the sidewalk if you feel it is safe for you in your individual situation. In a busy downtown, your best bet is probably the street, anyway. sidewalks will be too crowded. Don't believe people who tell you to ride in the road no matter what/where. you do what you feel is best for you. In most situations sidewalk riding requires additional vigilance and reduced speed.
__________________
"Think of bicycles as rideable art that can just about save the world". ~Grant Petersen
Cyclists fare best when they recognize that there are times when acting vehicularly is not the best practice, and are flexible enough to do what is necessary as the situation warrants.--Me