Stay on Fremont ST....anywhere from the Plaza to Fitz, you're fine. Avoid walking to the El Cortez, pretend the Western doesn't exist, and stay off of Ogden (Lady luck, Gold Spike). There's plenty of security patrols on bikes as well as Metro & they're doing a pretty good job of policing the place.
WATCH YOUR WALLET THOUGH!!!!!! Pickpockets are probably your biggest problem...especially if you're on the street during "the Experience" shows....and stay off the side streets if at all possible.
I'm downtown all the time in LV...never had a serious problem
MP