I also like that there's disagreement on all sorts of minor issues without anyone being bigoted or evil, or painted as such.
Penny's belief that "popular is better," to Aggie's annoyance. Rob's approval largely because he thinks that Aggie is a better influence than Rich, which Aggie latches onto in only a half-joking manner. All three parents, especially Rob, fearing that the couple will be facing social assault, which the couple fears not. And Lynda telling them to take things slow, which Aggie, at least, will ignore completely.