What might also help you to get a deeper imagination of what your VSTis and synths are capable of pretty fast is by writing a little test MIDI as just a simple sound check music project.
This MIDI should be around 25 to 30 seconds long, play within around 1 or maximally 2 octaves and contain at least following things:
1) a little groovy melody sequence which contains a big variety of velocity dynamics which you can set for each note between the values 1 to 127 (so, for example, create a melody line where the values of the following notes are around 85, 62, 90, 112, 127, 103, 74, 54, 27, 1, 16, 33, 49, 95, 57, 68 - with the help of this you can get a glimpse on how much effort the developers put in the sampling of different velocity dynamics and different expressions which come with it)...
2) a few chord progressions ('cause VSTis and synths may sound very different with just a one-line melody and complex chords - so, you can get a better vision for the later use of the VSTi or synth in your later music projects)...
3) and at least one very long (around 15 seconds long) legato note (with the help of this you can check out how the long played notes will behave - depending on the VSTis and synths I have checked and which I use myself, legato notes of different VSTis and synths might behave kinda differently - so, some will just fade out in silence after a while, some might behave like endless loops which won't drop the volume at all and others tend to behave rather irregularly but can create pretty cool effects sometimes.
With such a little self-written test MIDI, you can get a very quick and deep look into the potential of the samples behind your VSTis and electronic synths.
Just select the VSTi or synth you want to check in the track with the test MIDI, and then maybe set the right octave of your notes to match the VSTis and synths.
Make sure that you have activated the loop mode on your MIDI object (so that it will be played over and over again).
After a preset of the VSTi or synthesizer has been played completely through the MIDI object, check the various key combinations of your VSTi or synthesizer for the next passes and then move on to the next presets.
At least that's what I do after I want to check out some new (or old) VSTis and synths in a very fast and efficient way.