I find the Dentist terror pretty amusing. I mean, everyone is afraid of dentists, now this one is a powerful rich fiend. And then that his wife, (reminds of someone like Imelda Marcos) was actually a prostitute (or so Randy is told).
I was thinking back to Gravity's Rainbow and how Pynchon presents WWII vs Stephenson. Is this also going to go back to the Cold War? Actually, it's interesting that G.R., unlike Underworld or Crypt., does not jump back and forth between decades constantly. Perhaps Crypt. is more along the lines of Underworld. DeLillo shows the connections between the Cold War and the 90's, and perhaps Crypt is examining the connections between WWII and the 90's...
In addition to your thoughts, I think it's interesting that like Infinite Jest, Cryptonomicon sticks to two distinct but seemingly parallel universes which will come together (albeit here in different time periods) whereas GR (Mostly dragged out through WWII but with distinct fragments in the past) and Underworld (1950's-90's)travel across a broad sweep of time