For the Sales reps in/out, have you considered assigning to the Sales Team and adding/removing reps as they are available? That would prevent changes to the workflow directly.
The ideal would be if every user had an Online/Offline toggle. Then, the “Rotate to Owner” workflow item could have a “Rotate to All” or “Rotate to Online” option. I have a Workflow designed to handle all incoming Service (Cust Support) tickets that balances them by type. Everytime one user is out, I have to remove them from the Service Team then add them once they’re back. I don’t know if this resets the round-robin/balancing algorithm. It would be much nicer if each user could mark themselves as Online/Offine. An admin should have rights to change status as well.
Its annoying that this option (sort-of) works in conversations, but nowhere else in HubSpot.