We've got Redshift reserved instances and due to growth, we need to upgrade our node type soon (even in the same class!!). But because you can't reuse, recycle or sell the reservations between node types, we have to let all of our small node reservations expire before, complicated by the fact they were already bought in several layers.
There's no reserved instances market for Redshift (all of this looks like not very well thought out from the beginning) and it took us hours to finally come up with a semi good plan to do this (which will still cost thousands of dollars in lost expired instances). All of this was completely unproductive time in regards to our product, so the antithesis of what AWS stands for.
Managing financial matters on AWS is such a royal PITA, I'm so glad we switched 90% of our stack to Google.
They even give you a big fat yellow warning sign directly in the console: "Want so SAVE money? One click here and we'll resize your instance online instantly." Leave it on for a month and get nice discounts automatically. It's heaven.
(Yes, BigQuery. I'd LOVE to, however there's a lot of very good reasons we're still on Redshift...)