I wish I could justify using SQL more. It's just way too easy to use Dynamo. Unless my data is complicated enough to warrant a relational model, it's going in Dynamo.
That is kind of the problem, DynamoDB - and other NoSQL database - allow you to just start building your app, without any real thought about what data you will need and how it will be used - but you are often shooting yourself in the foot to not map this stuff properly out in advance.