My $0.02.
I would never choose Coral Reef for the view. I've never, ever understood that. Go into the Living Seas exhibit area and look at the tank(s). The view is much better, more interesting, and you can walk around without worrying about ruining anyone else's meal. So unless the food is the draw (and for me, it is not), don't go there. If one is going "mostly for the view", then I would advise simply spending a little extra time in the pavillion.
The food and atmosphere at Biergarten is far more unique. When I want seafood, I go to bluezoo or Flying Fish. But there isn't anywhere else on property that you can replicate what Biergarten offers. Now, having said that, you obviously know your kids best. German Oom-Pah music and polkas are not every kids' idea of fun. Many will love the place. But I could see others who might shrug it off as a place for the geriatric set.