AbigailII: What I would like to suggest is that possible a setting for a game could be "Max amount of vacation days to use for game 1 person can use".

So for example, 5 days max vacation days - so someone can use vacation days, but after using 5, the vacation days will not work for that game anymore.

On one hand I think there are already a lot of possible settings for games, but I think this one would help those like you who don't mind people using vacation & time - as long as it is not abused.