An update for those who care...
Since I originally started this thread, I had a mysterious week and a half of no reboots (no app or habit changes), then just as quickly it's back to at least one per day.
It definitely happens more when I am on the go (traveling or around the office), so I still believe it is related to the ongoing data connectivity bugs. If I'm home all day it may happen once. If I am out and around the city or back and forth to work, 2-4 times a day.
The recent build 748 made some improvements in many areas, but rebooting is not one of them.
I'm an engineer, so I got pretty active on the Motorola support forum about this and did a ton of testing, log collection, and research on the problem, forwarding the details to their mod who forwarded them to Motorola engineering. The mod was grateful, the silence from engineering was deafening.
To get a bit technical...
What I had found was that the Dalvik VM (the virtual machine that runs all of the phones apps) is getting to a state where it is unable to free enough memory through garbage collection, then starts killing apps, then eventually has an out of memory exception and the phone reboots. Normally the DVM killing off non-core apps is enough for the phone to recover (usually one of those apps is misbehaving). However, I don't think it is allowed to kill core apps (part of the OS / basic operation). So, my guess is that part of the OS has a memory leak under certain conditions, and the phone can do nothing but run out of memory and restart. Because the issue is aggravated by signal changes, and there are a percentage of phones with data connectivity bugs or VZW network issues, it stands to reason that the leak may come from that same module.
Couple that with Verizons LTE network being batty in some areas. I have heard that LTE on a CDMA network is a non-standard setup, making Verizons system very, ehm... unique.
I also discovered that when the phone connects to a known / configured wifi access point, the bluetooth goes off line for a few seconds while the wifi handshakes and initiates. This is repeatedly reproduceable (at least in my case). The hands free in my truck reports disconnection every day as I pull into the parking lot at work, and as I pull into the driveway at home. Most times the bluetooth on the Razr then has to be toggled to get anything to talk to it again.
Bottom line - the radio code on the Razr is still flaky, the network is still beta, and that could very well be the root of the frequent reboot issue some of us have.