I've also tried to build some GUI tools for BIND. It's not that easy.
I was only able to build some Perl Scripts so that people with low Linux skills can manage the zones..

In the end we changed to PowerDNS and built or own GUI with PHP/MySQL.
Our Users are happy with it and they don't need any skills except of what they put in their zones :-)

But we've only about 800 Zones, don't know how good PowerDNS scales in a huge Environment