Okay, so my band plays a swing song. Should be simple enough; the main progression is B B E D with all chords being major (I never said it was diatonic...) The problem is the horn melody, which hits heavily on the minor 3rd. By this I mean that D natural is a significant note that they're repeatedly banging on, rather than merely a short passing tone. The sick thing is, with guitar and horns playing, it doesn't even sound bad like I'd expect it to. However, I'm rather stumped as to whether I should be playing major or minor 3rds over the B and E chords (experimentation proved to me that major 3rd is the only way to go for the D chord). Neither sounds obviously right or wrong to me. Changing the horn melody is out of the question, and when I made the guitarist play Bm and Em instead of major chords at practice today, that sounded like crap (didn't fit the song AT ALL). So I ask my more experienced brethren, how would you deal with this song? Major 3rds? Minor 3rds? No 3rds at all? All insights welcome.