When I was in the LV Marathon last year, it took me about 1.5 hours to walk from the Mandalay Bay to the end of the strip (past the Stratosphere). I walked about 3.0 miles per hour, so your speed may be faster. (It was my first marathon!) Also, I walked in the street at 6am, so it was not hot yet. When I have walked it in the heat, I wanted to shoot myself in the foot! Be smart and don't walk the whole way in the heat. At night or in the winter, it's ok.