Rp,
I'm not going to insult you by suggesting ways of orchestrating for punchy brass, but simply offer the following based on my own experience, and observations gained from study.
You've raised a good point and as there are those who may read this starting out on their musical journey, who may wonder how they can achieve a punchy sound with VSL without having everything playing at once.
The biggest impact from brass comes with unison writing for instruments of the same type, then octaves, then in the trumpets with close three part in the upper part of the treble clef with the lead trumpet sitting on or near the top line.
Trombones are well suited to stronger dynamics near the G in the top of the bass clef. That's the 'meaty' part of a tenor trombone sound, and with the bass trombone in his favourite place doubled an octave lower, makes for a strong base for the trumpets to sit on.
Then articulation makes a difference too. Trumpets in unison playing detached staccato notes at forte or above will cut through almost anything, with maybe the exception of the piccolo in its upper register. The thicker the brass section orchestation, the less defined it is, as each instrument effectively cancels the other, particular with the horns included.
So much music today is written for stopped horns, that i wonder if they feel they're only being appreciated for the crackling noise they make rather than all their musical skills! Fanfare statements written near the G low in the Treble clef give horn players a chance to make a significant noise without losing tone, or having a hernia!
As I said, i'm writing this not to be disrespectful in any way, but with a view to others who may be starting out, and will read this thread with a small library of experience rather than a large one. And for those who are starting out in the wonderful world of orchestration, the following tip will be useful. When writing for a particular instrument sound at a loud volume, thin the orchestation 'around' the instrument a little. E.g. When writing a trumpet line about an octave above middle C, it would be self defeating to have the violins and W/W playing long sustained notes in the same pitch.
General rule is question and answer.
The trumpet plays the question, and the orchestra answers. If the trumpet section has 'fanfare' type lines, give them the room to be heard, and don't muffle them with long and sustained tremolos in the same pitch or place. (One cancels out the other.) To create a 'busy sound' that the brass can compliment with sharp attacks, remember the important role of Rhythm. (Examples can be found in Beethoven, Shostakovich, Saint-Saens organ symphony 2nd movement etc.) two alternating Rhythms alternately scored between small groups of instruments playing 'stridently' can create far more chaos, than a never ending stream of loud percussive effects, or endless scalic string runs, which become dull to the ear and possibly irritating, in a very short time.
If you want a sound colour to be heard, and as brass are far more effective and 'punchy' at musical statements than long sustained dynamically strong notes, here's a tip.
Imagine you've tipped a bag of marbles onto a table. They are all close together, and although there may be one or two that by variation of colour, may stand out a little, the general impression is one of 'mass'. Pick one marble in the middle that represents your chosen featured instrument, and gently move the others a little further away from it, until it stands apart from the others. In this simple analogy, use the sinlge marble as your statement instrument (be it brass or something else). The rest of the marbles represent your orchestra, giving the statement instrument 'room to move.' The rest of the marbles can be expressed in harmony, counter melody, Rhythm or a combination. As long as the lone instrument has a little space to work with, he will be heard clearly.
Hope this helps those who are starting out, and remember it's important not to lose your marbles!
Regards,
Alex.