StarDestroyer.Net BBS

Well, in TESB, the Falcon does go up, down, and pretty much everywhere when it's being chased. Plus, if you look closely at the background during the Coruscant battle, it does become clear that there's ships fighting at all sorts of crazy angles (although this may have to do with shot placement than anything).

What about the battle of Endor? It's been a while since I saw the movie and I only have the OT version but I recall fighters being all over the place in three dimensions too.

Good points, yeah, the space battles are pretty 3D and non flat.