We (adtech) use a very similar approach. We're consuming a ton of data through Kafka and then using Secor to store it on S3 as Parquet files. We then use Spark for both aggregations as well as ad-hoc analyses.

One thing that sounds very interesting and worked surprisingly well when I played around with it was Amazon's Athena (https://aws.amazon.com/athena/) which lets you query Parquet data directly without relying on Spark which can get expensive quickly. I wouldn't trust production use cases just yet and it ties you more and more into the AWS ecosystem but might be worth exploring as a simple way to do basic queries on top of Parquet data. I suspect it's simply a managed service on top of Apache Drill (https://drill.apache.org/).