I own planetes already, and have watched that series several times. Definitely a favorite of mine.
When I talked about "preachy", I meant how a lot of anime get into these long drawn out whiny monologues that just completely castrate the pacing of the show. I like exposition, especially when it's interesting (e.g. several ghost in the shell episodes), but man I can't stand the emotional soap-operaishness that I've seen in a lot of shows.
Samurai Champloo is one of my favorite shows as well, and in a lot of ways kind of reminds me of cowboy bebop (probably because some of the voices are the same in the dub).
I'm just looking for more anime in the same direction. Serious, but not soap-opera.