3 copies of your data can still be vulnerable to the same disaster.
That's what stood out to me about the AWS data loss in Bahrain and the UAE. AWS said it couldn't restore access to data hosted exclusively in its Bahrain region or in an affected UAE availability zone.
3-2-1 backup rule is a good place to start: 3 copies, on 3 different types of media, with 1 copy offsite.
For me, the real question is what could take out every copy at once.
Multiple availability zones give you protection within a cloud region. Surviving the loss of that region requires a recovery plan that reaches beyond it. Even then, the location matters.
If you need your data to stay in the US, you have more room to work with. AWS has 4 commercial US regions: N. Virginia, Ohio, N. California, and Oregon. Keeping data in the country doesn't force you into one region.
Pair an eastern region with a western one. Ohio and Oregon, for example, are far apart and on different major power grids, which lowers the odds of one regional disaster hitting both.
For data you can't afford to lose, I would also keep a recoverable copy outside AWS, still in the US.
A different provider's US storage or an encrypted offline copy you control adds protection against a problem affecting your provider. Make sure you can access that copy and its encryption keys independently.