I also go by the listener's perspective on drums. I changed everything on my synth (ya, well snyth drums) to match listening to it. A person is not on the stage, although that is another option which I suppose can be done. So with that in mind:
The bass drum is never in the center (unless mono PA) so it is left 3-5%, snare right 3-5%, toms getting bigger from l and right more (for in front of bass drum type toms) to big floor tom - about 25% left, while ride cymbal usually on left also is 30-35%, and hi-hat is on the right after the snare at about 25-30%, and crash cymbal (ride two) is about the same as the other ride but on the opposite side. (that is on the synth).
So when drums are used it is panned 100% L and 100% R to take up the entire field.
Vocals in center, bass guitar never. Usually I been using R side (as listening) between 10-40 %, because the bass guitar player is not on top of the drum player.
Guitar more to a side and quite a bit all the way to 90% and keyboard player the opposite side about the same depending. Anything else thrown in and I imagine a bigger stage and try and put the instrument playing where the player will be.
Oh, and then you got sounds panning left to right or right to left or wherever and like flying depending on what sounds or music that is playing.
Even forwards or backwards into the mix if appropriate.
3D with stereo image of speakers. (somewhat)
Well, that is about it, and vocal harmony would be off of the lead vocal on both sides but not to far off.
Adjust and listen and adjust and listen making sure you have a stereo image coming out of your speakers (that represent a stage perhaps) and have at it.
Any speakers usually will give a image like that if used properly and you are in the center listening (because it is all a virtual reality) anyway.