Don't forget Physical Modeling a la Sculpture in Logic.
As for ROMplers. I make all kinds of cool music with my Kurzweil K2600. Check out "A Little" on my MySpace page. It was actually done entirely inside my ROMpler. Even the vocals and guitar were sampled and messed with. The song features lots of sampled trumpets, bassoon, tuba, clarinet, and 808 for the drums. It might be better with real players... but my client didn't have the bread to hire all those people, and I kinda dig how it sounds just the way it is.
www.Nebulost.com It's the third song down.