Okay, for my side of the cast:

Klaus: 8 inches. (horrifying)
Liam: 7 inches (tall skinny boy's are hung. typically.)
Desmond: 6.5 inches (mad that he is smaller than his nephew.)
Engel: bigger when he was younger, shrank a bit with old age. 6 inches. He's a grower not a shower though. Probably only three inches soft. Embarrassed by the fact he shrank, wants to get some sort of pump for it. Doesn't really need Viagra, (yet)
Heinrich: 7 inches. Also a grower not a shower, struggles to stay hard. Has to take Viagra. Through determination alone he is able to fuck Neomi. (constantly in a state of perversion when it comes to her.)
Lev: 5 inches. Average and not ashamed of it. ("I still know how to use it, no?") needs some help getting hard and staying hard, however. Doesn't like to masturbate, forces Marble to do it for him. Gets irritable when he hasn't 'had any' (rape) in a while.
Cen: starts crying Please don't make me say it. he's not human he's 7 feet tall please don't make me think about it

spiritual penises:
Autumn: 10 inches in her mind, probably a 5 incher. sorry autumn.
wisteria: SPIRITUALLY that dick is 12 inches