baggersup - your solution only works with a stupid airline that charges for seat allocation even when you have paid a full fare on a full service airline.
If you book seats on a full service airline, you should have the ability (like Lufthansa) to select your seat well before check in and so the airline knows who is sitting where. Also, any group booking (family or business colleagues) are in the system as a single reference and the computers should be able to account for this when setting out the seating plan.
Any airline that cannot/will not do this, is living in the dark ages.