No need to play 18 interleague, and I really think they should limit the "rival" series to one each year, switching parks every season. 18 is no more than anyone played this year, and allows each team to play each other team once every 3 years, while still allowing for a "rivalry" series each year. It would be 4 series every 3 years with the rival, which is less than it has been (which really has been excessive), allowing each team two home series with the rival every 3 years. This would also completely balance out the schedule per division aside from 3 games. Which, out of 162, is pretty good.