My thinking is that the biggest advantages we'd have as a modern society is that it would be faster to build and take fewer people. That only makes their accomplishment far more impressive, though.
Well, to my mind the biggest difference should be how you treat the people working on the project.
I have heard different gospels about how people were treated and felt either compelled to their horrible slavery tasks or honored to be part of the construction of a holy monument of your revered living-human-deity.
Now the biggest challenge today would be probably to sell the project politically: even Mao and Stalin didn't have the political power (or will) to waste so much resources on such a useless rock pile – tourism and archeological documentary apart.
