Moving all connections/processes from one instance to another

On our 2 node cluster, we want to perform maintenance on one node at a time.  We have a service in CRS that attaches to the instances on these 2 nodes.  When we want to do maintenance on node 1, we would like to redirect all new requests from that service to the instance on node 2.  At the same time, we want all currently running processes on node1 to finish before we start the maintenance.  From what we've read about RAC, this is one of the main selling points.

Can this actually be done?  How should our service be configured?  What srvctl commands are issued to make the switch?  I've been testing various combinations out on our test cluster and can't get the desired results.