For an HA setup I would highly recommend using streaming replication with synchronous commits. There is no reason to risk losing a single committed transaction in a HA setup. As far as managing the system which I believe your question is more about; that is going to depend on your environment and there are numerous cluster solutions out there; personally I use a CARP based solution. For DR it’s more customary to use asynchronous replication due to the high latency in most DR setups thus there is a risk of losing committed transactions.
