a 40 gallon sump is a decent size for up to a 200 gallon tank IMO
.. ~20%+ main volume or there abouts..
I would try to get a bigger sump.. thats JMO
is that amount of lighting over both tanks or just your 220?
a 12 inch sandbed is ALOT of sand IMHO
.. but again.. thats your call.. :P
I would add some base rock to the live rock.. to total 1.5-2lb/gallon of system volume..
are you coarls (Im assuming these are reef tanks) compatable chemicaly.. ie do you have SPS
corals prodomantely? I would try to avoid softies and SPS
in the same system if it was me.. then again if you use plenty of chemical filtration and regular water changes that could be doable..
these are just idea's on my part.. in the "what would you do if this was your's" sort of answers.. I would love to be able to have that kind of tank space.. but I dont trust my current home with that kind of static weight.. good luck with this project..
as far as the laundry room/tank room goes... I would be conserned about the laundry chemicals like bleach being very well controlled (in other words, do you have children that might be in the laundry room? or enough space to give you enough room to keep the laundry and fishtanks good and seperated?)
does the door have a draft? is it an exteriour door?