The only "standard" is that 97% of films will ONLY have static non-movement ambience or pads in the surrounds. There are of course exceptions to the rule like you've mentioned. Most producers / directors never want focus to break the story line which is almost always up front and center. There are again exceptions - like something scary coming from behind, but this is VERY rare. Also, DUBBING engineers are going to be the one's who want to make that call.
BUT, as I said there are exceptions. The most notable exception is IMAX films. At least some of them (depends on the director.) You can do some pretty wild things. I did an IMAX film awhile back where the director/producer wanted things wild and COMPLETELY surrounding the listener - like you were inside a brain.
Arpeggiators are no good, because you can't break them out to easily, but if you WRITE and manually program a sequencer style line, you can then copy it to 3 other tracks and spot erase notes, then record each mono part in 4 passes and pan in the 4 corners. You can do similar things with percussion. It makes for wild instantaneous jumps (no panning necessary) that are very effective in blowing your mind.
I also did a lot with marcato strings - making them jump around. After you write you have to deconstruct the lines, copy/paste on tracks that are assigned differently in the surround spectrum and then pan accordingly. If you're using real musicians in a room, it's more difficult, but still do-able. They are not great about playing cut up lines on paper. Best to record as a normal line, and then edit afterwards. (Unless it's simple enough for them to pull off)
Do not neglect delays. These often work best of all.
Consult with your director before going down a surround path with any discrete and percussive elements in the rears....