Just a quick note – MS just released a Windows hotfix for AlwaysOn availability groups (AGs) that improves failover times if your deployment is using Windows Server 2008 R2 for the Windows failover cluster. I highly suggest that you evaluate this if you are thinking of deploying AGs.

I also suggest you evaluate SQL Server 2012 Cumulative Update 1 which may also address some things related to AGs and other high availability-related things (for example, this for DB restores and this for disk validation for FCIs).