This is just a quick post to help anyone else out there looking for the same information.  OEMs sometimes get creative with their WMI implementations for some reason, particularly when it comes to providing CIM_TemperatureSensor (which is pre-v2.2 CIM schema).

After much research and browsing WMI hierarchies, I've landed on a set of queries that properly gets the info from most servers (all in our environment).   YMMV.

Dell and HP both inherit the CIM_NumericSensor definition from the CIM (Common Information Model) 2.2+ schema

HP

CIM standard schema (query in \root\HPQ):
SELECT * FROM CIM_NumericSensor WHERE SensorType=2

HP's MOF extension (query in \root\HPQ):
SELECT * FROM HP_WinNumericSensor WHERE SensorType=2

Most HPs report for every sensor in the system; although the guide is specified for HP-UX, their definitions are available on their site on pages 3-6.

Oddball HP_Health extension to WMI (query in \root\WMI):
SELECT * FROM TempSensorInfo

Dell

Dell's MOF extension (query in \root\CIMV2\DELL):
SELECT * FROM CIM_NumericSensor WHERE SensorType=2

I can only seem to get "Ambient" temperature readings from the Dells via WMI, although they do provide more detailed information in DRAC.  Note also that their readings are multiplied by 10.