What kind of people benefit and what kind of people lose on a bitcoin standard?
Those who believe in the future of Bitcoin in my opinion are the lucky ones if the direction of the global economy. I think no one is harmed because Bitcoin does not force people to have it because Bitcoin is just a peer to peer electronic currency system.
How would it impact big companies, banks, and governments, and how would adoption speed affect all of that?
The impact on big companies like banks is that they don't benefit from transactions like they do from fiat through percent interest and so on because Bitcoin doesn't involve a third party, just the sender and receiver.
Simply put, the faster the Bitcoin adoption rate, the better. If for them government agencies including banks, they will feel the impact themselves.
To be sure, Bitcoin is not like humans who are hostile to the government or so on, but Bitcoin is an alternative currency according to the understanding of people in general.