I can share some topics we dealt with. We succeded where the topics had no negative financial impact on the company - and failed everywhere where it could have
Sabbatical / Unpaid vacation
Basically, I inform all Circles I have a role and see if there are any tensions. After that I trigger HR/Payroll, but they just "execute" (no management-like decision needed anywhere). I've never heard of a problem here; people know there is a high risk the person requesting time off will leave the company if the request would be denied.
Reducing or increasing pensum (workload)
I just reduced my working time for personal reasons. Basically same procedure like sabbatical. Inform, look for potential problems (tensions), execute.
Our company knows a construct called home-circles. Simplified, this is where my salary is paid from. The Lead Link (in charge of this resource) had to agree formally, but it came clear he basically cannot have a real tension with my wish to reduction since I could prove to him the reduction had now impact on the organisation (since I just finished a project). Therefor I knew this was more like a formal procedure; in fact I decided myself about my pensum.
So far I have not met a coworker that tried the other way (increasing pensum), but i'm convinced it works just as well (condition: you can proove the organisation has a benefit from it, meaning there is work to do and the resources are available)
We completely failed with compensation/benefits, also training and performance evaluation. IMHO the reason is simple: those topics are related and its about (loosing/spending/distributing) money.
Tough issues; maybe some things really are easier if you have a line manager making those calls
I would like to hear some other "apps" how others solved those issues