Looking at the RFP, one thing that I found interesting is that they want the locations, be it infill or Greenfield to be pedestrian friendly. This sounds like it wouldn't really work in and around Lehi so big plus there for SLC
Also, they do want to know where the cities rank on peak time congestion. As well as bike lanes nearby.
The more I look at it, SLC would be good and the 4th South location is optimal.
Depending on the layout, The 4th South and Main block could support 8+ million sq ft of space while still having open space, depending on the heights of the buildings. Using spaces directly East would easily complete a campus feel while also being easy access.
With the Bus, Train (Trax/Frontrunner), Highways (I-15/I-80) and Arterial streets (State, 3rd West, 7th East, etc.) there are few places in Utah that fit better than 4th South and Main.
I would think that this may extend further because of their full requirements, I don't know if there are many places that could support this to the same level as SLC. This may be homerism but it sounds like it was written for the 4th and Main location.