I'm not sure there are trends other than larger, flatter, brighter complexes. That is the only observable long-term trends. There are "fads" drive by new species but most of these just seem to merge into complex breeding. For example, consider armeniacum: it has been crossed into almost every species with some lovely results but most of the 2nd generation crosses are taking place in the complex line. Go see DrOrchid's breeding on orchidweb.
I must confess to be dumping maudiae types into "complex" as, again, most of the popular crosses are not very complex. Most of the inroads with these seem to be driven by the availability of new or rare species but, again, there is a lot of action on the front merging the maudiae types with complex line---consider the crosses with charlesworthii in the back ground to get larger, rounder, flatter, brighter dorsals...
Same thing for Parvie and Brachy breeding: larger, flatter, rounder, brighter/darker color...
Multi breeding seems to revolve around roths: taller, bigger, flatter, wider, longer-petals. These are now getting pretty complex as well the goals is either stonei-contrast or roth-size and -deportment. To my eye it seems breeding with sanderianum the goal is to get the long petal genes and then breed all the other traits out in favor of the roth genes. But now most breeding seems to be producing plants that are mostly identical. Only bulldog-complex breeding is actually producing something like a trend. There is certainly a divergence now between big and small but otherwise: rounder, flatter, brighter color.
