If you have an ex and children, you've dealt with it: The Switch.
If your ex isn't a total deadbeat, he's going to spend some time with the children you had together, and you're going to have to see him. You're going to have to talk to him. You're going to have to be nice to him.
There's no good way to drop off your kids with your ex, unless maybe your kids are so young they don't know you were ever together, let alone that you're now divorced. It's not fun for them and it's not fun for either of you.
Someone should create a service. Maybe some kind woman who didn't quite finish her social worker degree could pull up in her standard issue silver Honda Civic and cheerfully transport your children for deposit into the possession of the man you once shared a bed with, and now can no longer share niceties with.
She can take care of the "how's work?" conversations and the "I'll get you that child support check as soon as I can" conversations and maybe even the "how's it going with that tramp you left me for?" conversations, too.
Until that service comes to market, though, we just keep plugging along, trying to make it as painless as possible. I found that the longer my husband and I have been separated, the easier it's become. What about you? Do you have any tricks to make the drop off go smoothly? Has it gotten easier as time has gone on?