First and foremost, SQL Server 2016 Service Pack 2 was just released today. There are two major improvements in it for AGs:
1. SQL Server 2016 now has full Microsoft Distributed Transaction Coordinator (DTC) support. SQL Server 2016 had partial support for DTC with one of the two scenarios (cross instance/cross platform), but not intra-instance DBs. SQL Server 2017 had both, and now that was backported so SQL Server 2016 supports all DTC scenarios with AGs. This is great news.
Click through for the other major improvement. This is in addition to yesterday’s notice regarding the distribution database.