I think I would have built it the other way (39" wide and 30" tall) instead. I hate the feeling of wet armpits
It is sweet that your wife & kids like the idea of a huge sw tank. My wife likes the hobby too (although for me its more of an obsession) and my 2 years old daughter loves fish & corals. She can already name many of the species in the tanks.
Looking forward to more progress reports.
Anthony