Michael - ISFJ. He's mostly caring about his son. Appears more T than he is because he is male and thus assumes a more male role, esspecially in his family dominated by STs. Ultimately, he's all about social responsibilities. First his son and secondly his family. When those two conflict, he's going for the first, his son. This is why he often plans to leave the family with his son to protect himself and his son. In the first episode, he's swayed by his sons wish to remain with the family.
GOB - ESTP. No commitment wanted by this one. Neither to work, nor to a wife. Once its time to settle down, he's backing out. Very competitive, very show-off. Talents are totally unchanneled, which is why he's not the one taking over the business.
Lindsay - ESFP. It-girl. Joins causes but not because of a reflected opinion, but more a spur of the moment. Is easily swayed. Kinda materialistic...
Tobias - ENFP. Psychologist, but got "distracted" by his new fancy: acting. Kinda lives in his own world, but is also very sociable. Enthusiastic but also unrealistic. Unsteady. Uneasy with the physical world.
George Michael - INFJ. Seems like a copy of his dad, but is more openly F. Thats because he's not bound to social expectations as much as his ISFJ dad. Seems a bit like a male Lisa Simpson concerning school. Awkward in social situations. Driven by ideas, not the physical world. ENTP-INFJ relationship between him and Maeby, both talk the same N language and both are drawn to the "wrongness" of that relationship.
Maeby - ENTP. Is different in key aspects to the 2 ESTPs in the series: less physical in what she does and what takes her interest, less driven by social recognition or materialistic gain. Her cons are more explorative, trying out what is possible. Quick witted, has lots of interesting ideas, but lacks maturity and "real" education to appear as ENTP as she really is.
Buster - INTP. Got totally trashed by his overbearing mother. Pursuits the life of a scholar but is entirely too unfocused to really do that. Hard to type. His emotions seem to be directed outwards, not inwards, which is why I take him to be INTP and not INFP. Inferior Fe often breaks out.
Lucille - ESTJ. Social status. Social status. Social status. But not the touchy-feely ESFJ-way. Is somewhat pulling the strings from behind the scene. But not really efficiently ^^
George Senior - ESTP. Healthier ESTP than GOB. Discovers his "spiritual side" in prison (inferior Ni), but turns it into a selling scheme. Was the president of the company, but ultimately, his wife controlled it.
Oscar - ISFP. Is a hippie, but appears somewhat awkward in social situations, never drawing too much attention to him. Often exploited by his twin brother. ESTJ-ISFP romance going on between him and Lucille.
Narrator - INTP. Connects the dots, makes sense of the story. Is never seen and never appears to want to get "unnecessary" attention, thus not E.