Are you talking about tiling the side of the vanity and having that as an inside wall of the shower? That wouldn't be a good idea. You should build a half-height knee wall between shower and vanity, then tile the shower side and butt the vanity up to the other side. And have glass from the top of the wall to the ceiling. And you'd want a double threshold shower pan so the edge looks nice.

i have 3 boys and each has their own bathroom---new build nearly 10yrs ago. at that time, i let them make their own choice (within limits) as to what they wanted. 2 chose stained wood cabinetry and my youngest chose white....at the time my oldest was about your oldest's age. i don't have any comments about color/decorating really- that's so individual and doesn't matter really except to the boy. i don't think young boys are terribly concerned about the 'masculinity' of the decorating! but, i can say that i was surprised at the storage space required by them as they got older!!! i would definitely stick with a vanity and try to design it with useful storage...i wish their vanities had more drawers, for example---i'd go for a good sized medicine cabinet, etc. AND, i'd think twice about white grout around the toilet/on the floor! (if i were doing it again, i'd look into floor tiles which could be laid with the very very smallest grout lines possible!

I like vanities that don't go wall to wall. Even though this one is in an alcove, we didn't go wall to wall. (Two separate vanities would also look nice, but definitely 30" - no reason to go as small as 24" since you have 7' in total)

i don't think they come in doubles, I am having no luck trying to paste the picture, it is similar to the dark vanity's sconces above, they are long and tubular. I will have to graph it out. Actually I think I will have to wait, because I have no idea where the bowls of the sink lie on this granite top. Ok, think I have solved my dilemma, I really need to wait for the granite top, not knowing the sink placement, and having one wall abutting the vanity. Then I shall attack it with graph paper.