Simon Pegg for a romantic line with bettyhume comical and dramatic. Someone to break down her shell. Any (but the oldest) of this girls brothers. Seth Rogan, Jason Segal, Kevin Spacy or James Franco as a pot dealer who'd be jackblanco's only friend because the man is an ass.
Females:
Alternative to the male pot dealer: Olivia Wilde, preferably as a lesbian. This girl's sister who is 2 years older and has at least 1 child. Kate Winslet as laurahall's eccentric and rich aunt.