Doc,
This has been a problem for a long time. Midi sounds terrible because it's synths and oscillators trying to imitate a horn. That never sounds good.
The better stuff is the sampled libraries. Unfortunately, the free stuff mentioned.... SFZ+ and the sound fonts that are free, are old technology and very often still don't sound much better than the midi patches. I too, used to use SFZ and fonts quite a bit. Many of the free ones didn't work or sound right so I stopped using them many years ago.
Over the years I have purchased a few really good products. Native Instruments Kontakt is a must have synth for general purpose music composition. It is sold by itself and also bundled in a collection of synths called Komplete. NI makes a bunch of packages of sampled sounds, including Session Horns
http://www.native-instruments.com/en/products/komplete/orchestral-cinematic/session-horns/ In addition, a number of third party companies make 100% compatible sample libraries for the Kontakt player. I've picked up a few of these in the $20 each price range. Better than midi....and they sound reasonably good.
I recommend Kontakt as the first step into the better quality synths that will do the job required. Lots of guys doing film & TV stuff use this synth as their go-to synth ... it's that good.
It's not free, and it's not the cheapest out there but it is a workhorse of the industry and for good reason.... it does a great job.
Kontakt is actually on the lower end of the price spectrum with sampling synths. I've seen quite a few really nice sounding sample library synths that are several thousand dollars each. Too rich for me.
Back to the lower end......
I have Sonar X1 and use these as plug ins.....
Currently, Cakewalk has DimLE and GPO for $50 for both.... they also have SFZ+ and Square 1 totally free.
http://www.store.cakewalk.com/b2cus/category.aspx?categoryID=39&cat=39Spend some time using google and Bing to search for free fonts and samples.... you may find something useable. I used to spend time looking for free stuff and I found a bunch on KVR.
http://www.kvraudio.com/ Most was not really much better than a good midi patch, and a large percentage was worse or didn't work right.
Good luck searching.