is it problematic to cluster across two datacenters w/aag?
PASQLDBA it depends really on how much data is being written to the database and the link between these two DC's and also how far out of sync you can tolerate the two servers keeping your RTO/RPO in mind.

This is by no means any indication of what your milage may be but we have the following setup running quite well.


2 Node Cluster, 1 node in each DC
DC's are a good 20 - 30kms apart
Fiber link between the DC's
Local SAN disks
Node and File Share Majority
Availability Groups setup, auto failover with synchronous commit


This houses multiple AG's with ~50 databases with no noticeable performance hit over the single instance it was on before.

Hope this helps.