The reality is that most business people don't have the time to get their heads around alien notation and ISO standards that so many people spend hours on linked in groups discussing and arguing about.
Stakeholders want clear messages and easy to consume material that is relevant to their needs as well as forming part of a joined up picture - architecture!
If your organisation follows a cost leadership strategy then your operating model is likely to be process centric with lots of focus on squeezing out every "ounce" of waste and cost. The BPM vendors are all about this and some of them market excellent tools to help create such models but what if your business is different?
If your reason for existence is not about the lowest cost to provide a comoditised product; but is about innovation and differentiation a process centric operating model is hardly of interest. The processes probably change case by case, week by week and keeping it all documented is going to be a futile waste of effort.
Operating models need to be structured to communicate the right things to the right people. So don't start with a methodology, framework or modelling tool and impose it on your colleagues. Start with stakeholders first and understand what is required.
If you want some more help in developing Operating Models then perhaps think about organising a seminar or one to one mentoring programmes from Dever Solutions Limited