Multiple seasons would be great. The most I've made it through with one team was 24 games, getting halfway into season 3. That was tabletop.
It can get tricky, because at the end of season 2, one player's team was so decimated that he started a new team. It was also tough to convince new players to come in with existing team with higher ratings. But I think both of those things are made easier with the online version.