I've seen sea otters at a number of zoos and aquariums (Vancouver, Seattle, Point Defiance, San Diego Seaworld, Shedd, Georgia, Monterey Bay, etc) and the Minnesota Zoo has the BEST sea otter exhibit that I've ever seen.
I think the grizzly would not easily be able to see the otters, but the visitors can look up and see the grizzly. I haven't climbed the grizzly rock to check it out from their perspective, though