A while ago when the price difference between standard storage and glacier was closer to 10:1 than 3:1, I moved a couple of bucket completely to Glacier using a life-cycle policy. Admittedly, I hadn't investigated how to reverse that process permanently.
I know the documentation states that I would have to "use the copy operation to overwrite the object as a Standard or RRS object", but I guess I'm unclear what that looks like. Do I just copy and paste within that bucket?
Restoration can only be done at the Object level, not Bucket or Folder. When an object is restored, it is a available in Amazon S3 for the period requested (eg 2 days), then reverts to only being in Glacier. You'll need to copy the objects out of the bucket during that time to keep a copy of them in S3.
The easiest method would be to use a utility to restore multiple Objects for you, eg:
Also, see Stackoverflow: How to restore folders (or entire buckets) to Amazon S3 from Glacier?
