We have 4 AlwaysOn High Availability Clusters. Not the same as Active/Passive but similar.
1. The only problem is with the cluster losing connectivity when VEEAM does it's backups.
We had to change the same subnet threshold (CrossSubnetdelay and SameSubnetDelay) default parameters.
2. Memory - make sure to give SQL plenty of Memory. Enough for Operating System.
3. Data/Logs/Temp on High Speed Drives
4. Native SQL backups not on interfering with VEEAM (VMWare snapshots) backups
They seem to be doing well. Over 12 months on Production.