SF yes I totally agree with you.  But what about NYC specifically Manhattan?  How do you make it significantly more dense than it already is?<p>The best answer for NYC is probably to aggressively gentrify as many neighborhoods as possible, which means (bluntly) displacing most lower income residents and moving in bicycle riding organic jam loving armies of hipsters.  This comes with a lot of challenges.  The biggest pressure release valve for Manhattan real estate prices has been the very successful gentrification of Brooklyn (and a few years behind is Oakland filling the same role for SF).