In my opinion, the Triton has the best stock string and orchestra sounds of any synth. The piano's are decent. My fave is the wide l/r piano.
The synth sounds are great, as are the bells, guitars, and rock organs.
This is the perfect synth for what you are talking about. It can do very moody, melodic film music VERY well, along with steppy, trance type stuff. It has a built in vocoder, plus dual programmable apregiators.
Check out the Triton reviews at sonicstate.com and harmony-central.com
Also, the MOSS option brings a whole new synth engine to the Triton, great for accoustic and analog emulations. To read about the MOSS option, check out the prophect and z1 reviews at the same sites I listed.