I like the idea of the wild card round lasting 2 days. You have a double header on day one and then a normal game on day 2 if needed. The day after that you start the division series. This gives a big advantage to the top seeded teams as they get to rest up for a couple of days and set their rotation while the wild card teams have their pitching staffs wrecked and don't get to throw either of their top 2 pitchers until probably game 3.
I also like the idea of playoff double headers.
Gross. Double headers are boring as ****.