Both of the AIBs publish extensively documented, detailed reports,
after
thorough investigations. I've tried, and failed, to find similarly
detailed reports on the NTSB web site. Are there any?

If you're sufficiently rich/important, a little more effort is put
into trying to figure out what really happened. Fosset's NTSB is a
good example: http://www.ntsb.gov/ntsb/brief2.asp?...FA277& akey=1
....not sure how it compares to RAIB/AIB reports though.

-Paul