Money in the bank to accrue interest (say 15% per round). I think this would add a element of "points vs. money" strategy.
Like this idea but 15% is too much. I started with $200k in the bank which by now would be worth $462k!!! That's more than most rookies have risen!!!
5% sounds about right to me.
I think the major change I would like to see is a one player on the bench nominated as your sub. If any player on your field is subbed off you have the choice to use your subs score, but only for one player.