"Change from orientation" to supplement "Change to orientation" rule
Others have called out "any change" to orientation as a desirable rule, but I'd like to see a slightly different change: the ability to select "to" or "from" in the current orientation rule.
Example: attached to an object that falls over a lot, a "change from top" would test for any falling condition, and a "change to top" would test for someone setting it back upright. This could be done with separate rules for each falling orientation, but a "from" option would make it more straightforward.
Vibration could be a replacement for this, although it depends on how sensitive the vibration sensor is; a hard orientation change is a much more reliable test for a fell-over condition.