Can you and your ex sit down and come up with what works best for the kids and for you guys? This is what my ex and I ended up doing years ago and it worked out fine. (meaning the kids grew up and have good lives and we are each retired, not friends but not enemies) I lasted one mediation session...
I am sure, though, that there are good mediators out there, it would be worth interviewing a few to ask about how they work to see if it sounds like a good fit. (((best luck)))