FE11 Marth : I don't know if it would be an advantage or not for Marth if everyone could visit the villages, as it can distract him from battle and experience. On the other hand, I also think that giving him experience for visiting and seizing would be good, since it seems fitting that, being the leader, he would also improve by doing his lord job. So yeah apart from that he is not bad, maybe a bit more speed would be good, since he often has trouble ORKO if he's not using his effective weapons.
FE12 Avatar : Just go back to FE7 Avatar, maybe with more screen-time, but his usefulness shouldn't be "I'm the best soldier around", but rather "Despite those crappy odds, my intellect has granted us this victory", or that's how I see what a tactician should be personally. And if he is part of the battlefield, why would he have to be a god tier character? Lower growths all the way for him/her.