Lots of classical pieces are written and performed with some spatial awareness.
Antiphonal choirs (two or more groups of singers in different places) were used in medieval and renaissance music and probably long before that. The apotheosis of this style was the
Venetian polychoral style which involved spatially separate choirs singing in alternation. This was particularly suited to and influenced by the architecture of St. Mark's cathedral. Pretty hard to reproduce via two channels.
Beethoven 7th symphony finale has the tune bounce back and forward between the first and second violins. To work, the conductor has to separate sections - firsts on the left and seconds on the right as you look at the stage. This transmits just fine to stereo reproduction.
Berlioz was a great innovator in orchestration and his 'Grand messe des morts' calls for 4 brass bands, placed north, south, east and west of the audience. More than two speakers required!
Following Berloz' example, later romantic composers often used these kinds of effects. Mahler's second symphony has an off-stage band. The composer's instructions are that they should be as far away from the main orchestra as possible. This works reasonably well via stereo but is much better in the hall. His sixth symphony has alpine cowbells. Albert Hall performances typically have them up in the gods, really effective if you are down in the stalls. This vertical panning doesn't really come over on two channel systems.
Plenty of modern composers have used multiple sound sources, with often very precise instructions as to their spatial arrangement. An extreme example, Stockhausen's Cosmic Pulses, plays 24 'layers' of music through 8 sources arranged around the audience. The sounds travels all around the listener. This might work through a surround system but I suspect you really need to be there.
In comparison with this, the stereo panning effects in rock music are pretty unambitious.