At this point in time, I'm with you, I'd kind of like to see some more episodes where, oh, I don't know... Arthur is the focus. Arthur's barely even been a minor focus of the season so far, and we've had more episodes where he's completely absent. I get that the show's been on for so long and there's so many other different characters that they can explore, and they have, but it's still Arthur's show after all, and it'd be nice to see an episode where's the focus... and not forcefully out of character like in "So Funny I Forgot to Laugh."
Aside from that, Marina is really rising in popularity lately, mostly because she's cute as a button, but also because she's the kind of character whose not overly extroverted yet not afraid to speak her mind when she has to, and certainly doesn't let her disability limit what she can do. Admittedly - and this too would be a little too for the friggin fans - I would kind of like to see an episode where a boy develops a crush on her, but when he finds out she's blind, he doesn't know how to handle the situation, though she's the one who puts a stop to anything before it starts, not because she thinks nobody would want to get involved with a blind girl, but because she's simply not interested. That, or they could do another schmaltzy anti-bullying episode where somebody at school keeps picking on her for being blind, tripping her in the hallways, or jabbing her in the back with pencils and stuff.