I never asked deposit for more than one month of rent. For certain area, I only asked for $500 (my releasing broker told me people are not used to pay security deposit in the area).
My experiences is,
Good area / good people: first+last+deposit(one month of rent)
Average area / good people: first+last+no_or_little deposit
I so far don't have experience dealing with renters for 白菜房。