I like the idea and would like to see a demo if you get one ready. I agree with the previous suggestions about using and ameliorating the APIs instead of querying directly to the databases.
In my previous organization, we also struggled with the management of numerous big clusters and we developed a home-made Django web portal to satisfies queries and automation that Horizon could not do. I would be curious to see which functions have been developed for 'openstack-admin' and how similar the needs are.
Cheers,
Camille Rodriguez