First thing I usually do is convert all of the CC lanes into note expression containers. This way the all that expressive stuff binds to the notes and will quantize with them more or less in a ‘relative’ manner. Cubase fortunately has plenty of tools to go back and forth between keeping expressive data contained with each note, or free flowing on CC lanes as needed.
Next, I play with the humanization stuff in the track inspector. Some of that stuff can work in real time, somewhat random, and never ‘exactly the same twice’. You can allow weights and such to how much humanization occurs. Examples are humanizing the note on and note off events by a given percentage.
Next thing I do is spin off anything that was using a group ensemble patch and build sections from individual solo instruments. I’ll still usually keep the ensemble patches in the mix, but at lower volumes depending on if I want more punch and clarity in articulations, or a more lush and loose feel.
From there, if I need more I start working with individual tracks. MIDI Logic editors are among my favorite tools here…they just allow me to move alot of stuff in a more batch-like way. I.E. Find any note close to beat three from measures 12 - 16 and lower velocity 11%. I.E. Scale the CC1 events for that crescendo down by 5. Sometimes to do these sorts of edits I’ll need to convert my VST3 note expression stuff back out to CC lanes until I’m done.
On grooves, in general I find that Sibelius does a pretty good job of laying those before I export them (I.E. If I wanted a heavy swing, or a strong first beat in 2/2, or whatever). When it doesn’t quite get it right, it’s usually just a matter of mixing up the tempos a bit, and smoothing out velocities or volume CCs with the MIDI Logic Editor. In some cases with odd complex meters I might find it easier to just turn off the grid snap and set the groove manually note by note (again, having the expression stuff bound to the notes as VST3 expression events help when shifting stuff around in time).
If push comes to shove, you can even record your own grooves as a MIDI track and quantize to those…it just takes a little practice.
By this point it should already be sounding much more musical…so make your final touches to each solo player in your built up ‘sections’ to make them more like a real musician would do (micro tonal pitch changes [or portamento effects], vibrato/tremolo, dynamics, extra articulations, overtones and harmonics, etc.). Sometimes I’ll literally listen to a particular musician who’s style I want to try mimic a bit. If you listen closely you can pick up subtle things players do that can sometimes be mimicked a bit in sampled or synthesized instruments.
Towards the end I’ll consider adding ‘nosie’ (As in what it sounds like when an open mic just sits in an empty venue). Room and or crowd noise, instruments clattering and clanking, those sorts of touches. Effect chains, how things are panned out, and room simulation all come into play here as well.