We partner with Datastax as their go-to hosted solution for Cassandra; their support tiers don't include operations or instance management. We handle all Cassandra maintenance, ring expansion, daily backups, and upgrades. Upgrades are an interesting one, as critical updates to Cassandra sometimes require client updates as well. Since it is very possible for you to break things, we also handle data and schema rollbacks on a per-keyspace basis. The REST API is really cool because there are a a lot of Hector operations built in for data management (reads and modeling) you wouldn't have to do using a client. Secured access can be given to AWS private IPs or Security Groups as well, so you don't get charged for data transfer to/from ring from clients.