I like idea 1 much better than idea 2. I can't imagine a person who would read articles on instrumental rationality but not epistemic rationality. However, I think there are people on here who care about the applied rationality but not normative rationality and vice versa. This doesn't really apply to me, since I will be reading everything anyway, but I think that Idea 1 is both more useful for readers and more easy for posters to decide where their post should go.

I would however create a few more distinctions in Misc. I think that Meetup posts should get their own subreddit, since there are people who are just not interested in going to meetups. I also think that open thread and the ask a stupid question thread should be their own subreddits, since they get so much activity. I would make the list:

Main: As above, but it should contain only promoted posts.

Applied Rationality:As above

Normative Rationality: As above

The Future: As above

Open Discussion: What would have gone in the open thread

Ask LessWrong: A combination of ask a stupid question, and possibly some polling of opinions

Tangible Life: Mostly meetup posts, but also job openings etc.

Misc: Everything else

If this idea is rejected because people prefer fewer subreddits, I think it is still a good idea to start with a list of many subreddits, then ask the best way to combine some of them with misc or with each other.