Maintenance_work_mem = 1048576 – Figured Id allocate 1GB for this.
Do you know how often and when you will be creating indexes or clustering? We set ours to 2GB because of the performance gains. We've also thought about testing it at 4GB. We can do this because we know during the middle of the night our server load drops to nearly zero. If you know you have windows like that, then I would definitely suggest increasing your maintenance_work_mem. It's halved the time for io intesive tasks like cluster.