It was interesting for a couple of reasons, the first is that I tagged into some of the preparatory work and it was an opportunity to see my input become throughput (something that is important, but often lost in large organizations).
Secondly, as someone who is interested in the dynamic between public service mandarins and their political masters getting to see the dynamic play out in person (literally right in front of you) is fairly awe inspiring.
Finally, I was away from my home department for 13 months on an assignment working in a completely different field, so the chance to sit in on the committee as government witnesses gave depositions was probably one of the best (corporate) learning opportunities I've been afforded in a very long time. The back and forth between public servants and senators in the question and answer provided a richer experience then an ad hoc reading the transcripts ever would.
In short, I think you should keep your eyes out for opportunities like these and seize them whenever possible, its not everyday you can take a step back and (to mix metaphors) realize the forest for the trees.