Okay, those of you who've used popcorn...
What's to keep the group from picking one order that's tactically advantageous most of the time and just never deviating?
For instance, the group I'm running consists of a paladin, a fighter, a wildshape-focused druid, and a cleric. As things stand, if the cleric rolls a high initiative, she usually readies an action rather than going immediately; she likes going late in the round.
Something like 90% of the time, they're just going to go fighter-druid-paladin-monster-cleric. (The fighter often wins initiative, since she has the relevant feat.)
I like the popcorn idea if it actually
does vary and require tactical thinking, but--at least for the first round of every combat--I don't think it
would vary with this group.