This is getting so frustrating. I was originally running into these problems (departments not sharing/gifts not gifting/commuters not commuting/utilities not trading) in my private region on North America East 2 which is a server it looks like everyone is having this problem with, so I bit the bullet and started making a new region on West 4, assuming that a brand new server would work better. I built up a really solid industrial/power city and when I started to hit the wall and wanted to start my education/residential city I was unable to buy power or water from the power city and no one was commuting anywhere. I gave it a couple in-game days in both cities to see if it would work, but to no avail.
Then I popped back on my cities on East 2, mostly because I didn't really want to bother working on my cities in West 4 until the region play started working and I wanted something to do, and then lo-and-behold, region play was miraculously working for me on East 2. I could set up trade deals and watch the neighbouring mayor drive over and activate it. What was unfortunate was that I had lost all my mayoral momentum in those cities and had gotten so much better and made a way more compelling region on West 4. I hopped back over there, hoping that maybe everything was working now that East 2 was, but nope. My region on West 4 is still broken.
This is seriously, totally, completely frustrating. I just want it to work. Please? It's so annoying that I had a better play experience once I finally got in on launch day than I have on any day since then. Things have just gotten worse. It looks like they're getting better now, but It'd be nice to have an update on this issue. I assume it's related to the turning off of the other social features like leaderboards and achivements, so if the servers are so much better now can we just turn those back on please? Sigh.