The Salt is of the shelf, with some bash scripts on top to auto generate some config and make installation of a new server one script call.
We surely could put endless hours into Ops, playing around with stuff etc. but the benefit would be marginal.
Our DNS setup is simple, not much to say, we use DNS Made Easy for failover, we use S3 though I do not consider it "AWS" (S3 is comparativly cheap).
I've wondered about Mesosphere with autoscaling etc. but with adding a new VPS in seconds setting up Mesosphere/Kubernetes taking two weeks would take quite some time to amortize.