Jim - Glad you worked out. Being a veteran of 32 yrs. of domestic compromises I'd offer that you want to tread very lightly on that whole laundry room idea. I'd suggest a metal stand ( I like the PetCo "Brooklyn") a 20L on top a 10 underneath. Find a few plastic storage boxes at the $1 store. I 'd suggest you don't push the footprint of laundry space to hard. I'd also be clear what a Q-Tank is for i.e.. temp holding of fish/plants. That said don't debate from the plan.
While you reached an acceptable compromise (Great) you don't want your wife to feel she made a mistake. Some times the best compromises are not 50-50%. The goal is to have your wife embrace the hobby.
Glad this worked out for you.