Sayonara Zetsubou Sensei is rather good for intelligent writing, the main character is a teacher easily in his 20s. A lot of the characters are his class (which is about 75% female) but the cast also includes his random public figures and adults.
Ex:
The Kara no Kyoukai series of movies is also a good option, physics are approximately normal, everyone involved is at least college age, and there's a lot of philosophical banter. Especially the epilogue which is 30 min of pure philosophical banter.
That's just off the top of my head. I could probably name more after looking through what I've seen.