The REST API of NetBox coupled with how responsive the Digital Ocean team behind NetBox is to feature requests are hugely useful. The (relatively) recent additions of patch panels, and cable paths through them are very awesome for documentation.
Only feature I missed from OpenDCIM is the ability to simulate power distribution panel failures to identify what would power off when a particular power feed goes down. This is something which the end user would have to code.
I coupled NetBox with Ansible (JSON module) or Salt, and built a fair bit of automation like that.
With some scripting in (I used Python), system labels printed with barcodes, and a barcode scanner, rack audits become a lot easier.
Add a cross-check against MAC address records (on-host LLDP against NetBox, and both of those against your network discovery tool like NetDot[1] or NetDisco[2]), and you can get quite clever. There are commercial products which do that (they watch for ARP broadcasts and spanning tree change announcements), but they are pricey.
[1] https://github.com/cvicente/Netdot
(Updated: network tool links)
The Netbox Ansible inventory is mature, and you can use the netbox webhook feature to trigger Ansible playbooks. It's extremely powerful and is the root of almost all of my admin tasks now..
The governance ansible is excellent, the attention to detail coming from user feedback and pull requests really show when you dig into it.