Row 4 and 5 (on the PSR page), of the Strelets Russian and Prussian command set will help for some officers (though not in great coats), but I agree that what we could do with is an elites set with officers of varying lower ranks, musicians, NCO's, sandard bearers etc, mabe stick the marchers in there to make the numbers up-
(Yes it would be nice having a seperate full box of marchers, but how realistic is it that a compay will risk its capital on an entire box of marching figures?)
I just got my 1805 French in greatcoats, and unfortunately the officer wouldn't work very well;'he just has a bandolier with his sword scabbard, and what appear to be rolled up trousers.
The Russian officers had a sash and their swords on a belt.
As for the musicians, they have epaulettes (which I suppose you could trim off) but then they still have the wrong webbing and a very non-french look.
In fact the only suitable figure I can think of is the drummer in the rather flawed Italeri Prussians set, and he's a big boy. Still, I guess a drummer had to be fairly sturdy to schlepp his drum along.