You must not get me started on the music. Ever. :P
Well I pretty much loved the entire HGSS soundtrack, since I truly believe GSC had the best score ever. They were remade fantastically (that National Park theme? Just.. stop).
Usually it's the Battle themes that stand out most for me; my favourite Battle themes in HGSS would definitely be the Champion/Red battle theme, the Kanto Gym battle theme, and.. well, pretty much all the other battle themes in the game, haha. Otherwise, I like the National Park Music, Cianwood City's remix, the music for the new routes/safari zone, and... I'll just keep naming them all. I adore them all. :P
In DPPt, I quite like the music, too. Again, mainly the battle themes (such as Cynthia's theme, or Dialga/Palkia's theme- oh my lord). I also like the GTS music of Platinum, the Frontier Brain battle music, and Canalave City's music. I'll be totally honest, if I boot up my Platinum, I'll find more that I like. I really do like pretty much all of the music in the Pokemon games, haha.