If you toe in, as most do, having the tweeters in provides better time alignment with the bass section at the listening position. Unless you are very far away, it also provides a better image IMO, with the upper frequencies better balanced and centered vs. a bit of "hole in the middle" or exaggerated sense of stereo.
I prefer as far from the back wall as possible, or damped back wall, to mitigate comb filter effects from the reflected wave. Those mess up the image and tonal balance, driving me nuts. It's a short drive.
Distance from side walls is normally not critical because they are pretty directional above the bass, beaming straight at the listener. Close to the side walls can accentuate the bass a bit, and block some of the rear wave from reflecting off the walls, which may improve imaging but reduce "spaciousness". I favor imaging and tonality over "spaciousness", preferring to live with the sound field on the recording and not have the room be such a large factor, but YMMV.
FWIWFM - Don