Do you think samples are harsh? When I listen to live recordings, even during loud passages, the sound is still pleasing. However, with samples I have to constantly fight them. Quiet or loud, they are harsh. I'm really, really tired of doing this.
Is this just a matter of careful orchestration and midi/audio polishing, or is this just the nature of samples? Maybe I simply need better sounds? What's your experience?
My suspicion is that it has to do with instruments or sections being sampled in a room with no one else in it but those players. For that reason most sampled instruments cover more of the frequency spectrum than they would in context. That is to say: sampled instruments are generally more full sounding than they would be in context.
It might seem somewhat ridiculous but the body mass of other people and their instruments would certainly impact the sound. There is a difference between sound waves bouncing around in a barren room vs sound waves bouncing off of other people and (resonating) instruments, even if they're not playing.
If that sounds insane to you, consider that in some spitfire audio samples from AIR, you can hear the organ in that space resonating.
So the somewhat simplistic but truthful answer to your question is to use EQ. Now it's impossible to make specific recommendations but in general I find 200hz and 400hz to be problematic in almost all libraries because that's the area where there is a lot of low-mid build up.
Harshness is likely to be in the 2k range or higher, but that really depends on the instrument of course. Cinesamples has a whole EQ series on their channel that may help out:
Joël Dollié also has a lot of very good videos on EQ (and other processing) specifically for orchestral music.
The best thing you can probably do is get a reference soundtrack, something that is as unprocessed as possible, preferably only has the decca tree/AB sound in it and that isn't too dense in the orchestration, then try to match to that.
Narrowing the stereo image can also help in some cases because (hall recorded) samples generally occupy too much space both in the frequency spectrum and in the stereo width.
In addition to EQ you can also look at the attack and release settings if they're available. A shorter release can result in a drier sound which may be desirable if there are annoying frequencies in the tail. This Metropolis Ark 4 video shows that quite effectively:
Depending on how far you want to go, your final resort is to reprogram/resample instruments. It's not good for your sanity, but it will allow you to remedy serious imbalances in some of the commercial offerings and will allow you to make the necessary EQ, ADHSR and stereo width adjustments at the source.