Facebook, Reddit, and Twitter are particularly popular platforms for discussing about Bitcoin and sharing information.
There are a lot of great people to follow on twitter. Check out cryptomanran, venturecoinist, and cryptobully
Also there are some solid sites like Coindigo.
I like Coindigo so much because they put together all of the investing research you could possibly need for tons of coins. I can just read one article on there rather than having to do hours worth of research.