Well, there are subreddits for any particular political persuasion you may have - most of them have better discussion than the general /r/politics. There's /r/programming, but its a little light on content sometimes so I prefer:

/r/systems

/r/machinelearning

/r/netsec

/r/compscipapers

/r/coding

/r/compsci

/r/linux

/r/opensource

/r/csbooks

for the hacker part of me. There are also all sorts of other ones for any interests you might have - hard sciences, soft sciences, food, photography, sports, fantasy sports anything you'd like. Heres a spreadsheet with some other subreddits - its not nearly comprehensive, but it gives you an idea of what's out there.

https://spreadsheets.google.com/ccc?hl=en&key=ttpCnxB3rD...

TrueReddit is pretty awesome: http://www.reddit.com/r/TrueReddit/ . It's explicitly for "...thought-provoking articles, reddiquette, reading before voting and the hope to generate intelligent discussion on the topics."

In addition to what others have said, I'll add r/depthhub. It's similar to r/bestof, but it serves to collect all of the interesting and deep discussions that happen on Reddit. r/theagora is also great if you have a philosophical bent. It's an attempt to recreate the dialectic of the Socratics. Emphasis is placed on focussed rhetoric and honest argument, and to avoid logical fallacies.

/r/tldr is a nice digest, and a good way (for me) to find interesting stuff on reddit

I'd strongly suggest joining your state's subreddit.