Marco Polo and Denis and Francis both went through the dangerous/freezing mountains with horses and saw the "horns of a tremendous beast". But when Denis and Francis passed through, they had some advantages like good blankets, a tent (I think) and each other. All of this helped them stay warmer than Marco Polo must've in the 13th century with no shelter. 

Denis and Francis couldn't even get in the first time around, but on their way back they finally made it in. During their stay there was a parade-type thing where the crowd was shouting, "Death to America!" That was probably not something Marco Polo witnessed during his stay. They did however make a connection to Marco Polo the first time around. They went to Bukhara because it was the closest thing they could get to Iran, and Marco Polo wrote about his uncle and father's trip to Bukhara. 

I would want to travel to Venice because the footage from Denis and Francis' trip there made it look like a really beautiful place to visit. 

During their 712 day trip, Denis and Francis definitely learned to never take no for an answer. If they would have given up on any of the times they were told no (both times w/ Iran, on the train in China, etc.) they would never have made it as far as they did or experienced as much of Marco Polo's trip as they did. Because they always kept going they were able to make almost 2 years worth of memories and make a connection to their idol in ways they never could've.