Friends: You can get past the issues you have with Fischer's clock settings by adjusting the bonus you get for each move. For example, if the settings are 7/1/7, then you get an extra day each time you make a move, so you'll always have at least one day to make your move, regardless of how quickly your opponent moves.
I like the suggestion of some fast and some slow paced tourneys. One size probably won't fit all here and there's no reason to try and force that. ;-)