I really like 1& 0 City. Everytime I hear the music, I can picture the four people on a mission, running through the streets(Sakura follows Syaoran very meekly and closely), sneaking in the corners (security walks by, then Fai re-emerges from shadow and starts crawling his merry way off), and even breaking and entering (Syaoran kicks down doors or Kurogane cuts walls into pieces).
The Dreamers, I can imagine Fai dancing around the campfire with some villagers on the mountain.... Like that one with the bunnies
Powers Collide... It can be a lot of things- Syaoran vs. Seishirou, Kurogane vs. Seishirou (both gets beaten to bloody pulp assuming Seishirou is too good for them, which he was in X against Subaru). And of course, Syaoran vs. Syaoran (That dream where he chokes him through a reflection 0_0)