The only appropriate comment is that this issue is affecting all of our buckets, both in us-west and us-east. Replicating to another region would yield no useful benefits in this specific failure scenario.

I did some digging and experimentation, and so far it looks like you could keep a backup bucket in another region and use bidirectional replication [0] to keep the two buckets in sync. If something like this happened again, you could point your app(s) at the bucket in another region and keep accepting data. The objects would eventually get replicated back to the original bucket, and you could cut over again when service was restored. There does seem to be an appreciable replication lag, so you could run into problems during your cut where some objects had not yet been replicated, but your app ought to handle things like that gracefully anyway.

[0] https://docs.aws.amazon.com/AmazonS3/latest/dev/crr.html