One thing I notice with a LOT of American live action shows, be it comedy or drama there is far to much of, how barry said 'snap, snap' everyone talks to fast, there is no realistic pauses between speech. It's hard to say exactly what I mean but it's something that often bothers me.
Family guy is, in my opinion the best of that guys cartoons, infact I find the others almost seem like bad immitations of Family Guy with less entertaining jokes.
Whilst I do know exactly what you mean about the flash back type stuff and celeb 'mocking' I find the way the writers can highlight social situations and you can relate to those kind of jokes really, really funny.
The Cleveland show is really, really bad... REALLY BAD.