[ZGF4]

Cross datacenter replication is the missing piece from AWS. I wish they'd just roll out a hosted Cassandra or something identical

[jeffasinger]

While probably not what you're looking for if you're mentioning Cassandra, RDS does let you have read replicas in any region.

[manigandham]

You can use scylladb.com and set it up pretty easily. Stable, distributed and fast out of the box with a lot less maintenance.