Nebulous
Legend
Another idea. Every character has the same number of cards, call it X. The cards for a single character are not exactly the same. They are numbered from 1 to X. If the number on the card is equal to or less than the character's init modifier (or some type gradation), then that character goes then and all of his other cards during the rounds are ignored. If the number on the card is greater then that card is ignored.
Pro: Gradation taken into account, player portion of deck is consistent through out session.
Con: Ignoring multiple cards probably reduces the tension level.
Again just a thought.
I think I want to go simpler than that, minimal math and calculations. If a high Dex character or Agility feat character goes, they get 2 cards. Maybe once per day (?) they can elect to go before a monster at their choice, so it gives them a benefit from having devoted feats to being fast.