Two key points I want to address in one post. One, with an odd number of teams in each league there will always be at least one interleague series happening. I think the two leagues should have an equal number of teams, so this is the unavoidable consequence. As far as the rule differences, one suggestion I've heard that I like is to use the DH in the NL parks and have the pitcher bat in the AL parks. That gives the home fans a chance to see the other league's game. To make the rule difference less unfair one possibility is something similar to the rule about adding a 26th player for the second game of a doubleheader. One of the inequities of interleague play is that AL teams build their rosters with the DH in mind and NL teams build their rosters with no DH in mind. To compensate for that the visiting team could be allowed to make one totally unrestricted roster move for interleague play. Unrestricted means exactly that; they can sign a free agent to a 3-day contract or call up a minor leaguer without using an option or anything else they wish, as long as the player is not suspended or something like that. Two, the overly unbalanced schedule. My proposal, FWIW, is to have 14 games against each division opponent, 9 games against the other 10 teams in the same league and 16 interleague games. Against one of the other two same-league divisions there would be 4 home games and 5 road games and against the other division it would be the opposite. This would alternate every year. The interleague games would all be against the teams from one division. Two teams would visit you for 3 games, you would visit two teams for 3 games and the fifth team would be 4 games split two at home and two away. The division match-up would rotate so you'd play against every team over a 3 year period. This is mathematically balanced but that doesn't necessarily make it fair. It means teams from the Eastern time zone and the Pacific time zone would play more games against each other than they do now, and that does give a small but real advantage to teams in the Central and Mountain time zones. So I doubt we'll see any change in that anytime soon.