I feel it's simpler if the DM adjudicates the spell forces an involuntary physical action, given the examples are all physical ones, to avoid subjective "how would the target perceive this order" arguments. In the original AD&D version, the word had to be "clear and unequivocal" or it would fail, though surrender was in the example list. At the very least, the target would stop fighting.
Regardless of the word, as a DM I wouldn't want it having multiple effects or duplicating the effect of a higher level spell. That's abusive. It also cannot be qualified (e.g. "bash" that door).
Synergy: Ages ago I DM'd a 2E game where the command spell killed a 15th level character. The synergy came with the terrain. Barbarian player got in fight with other players and split the party by scaling an 800' cliff with his bare hands. At the top of that cliff was a red dragon that knew the command spell (back when dragons knew spells). Rather than blast him with fire, the dragon sadistically uttered the command "Jump!" Player failed the save and jumped, falling 800' to his death.
Now, that wouldn't work in today's game because the text was changed to avoid anything "directly harmful" to the creature. So, it'd have to be an unknown hazard.
So, I think the spell shines best when there's synergy with terrain. On a ship? Tell the target to "disembark" (shouldn't be directly harmful unless the target doesn't know how to swim). Know there's a trap in the back hall? Command them to "flee" and clear the way.