What I'm curious about is how to reliably transit service across Regions. ELBs live in a particular Region, so they don't help. You could certainly register m

What I'm curious about is how to reliably transit service across Regions. ELBs live in a particular Region, so they don't help. You could certainly register multiple ELBs to the same CNAME and do a limited round robin that way. But, even if you manually pulled the record for a downed region, you can't rely on downstream DNS to respect your TTLs. I suppose you'd at least be able to say something like "some of our users" as opposed to "we're completely down." That seems like cold comfort, though.