For a starter system, I'd just go 5.1. I also don't think Atmos is mainstream technology, yet. And I'm pretty skeptical that receiver could implement it well. If he is stuck on Atmos, he should rethink his budget.

I'm hearing good things about the $1,000 SVS package

http://www.svsound.com/speakers/prime-series/prime-satellite-5-1

I like Matt's suggestion about the Energy package and also Ken's advice about A4L.

bibere usque ad hilaritatem