Ask HN: The best system to store these metrics?

There was an interesting discussion in the Prometheus thread today, but I'm still trying to figure out what to make of it.

I have an app which records usage statistics on a per-instance and global aggregate in 5 minute intervals. I want to store request counts, source IPs, average latency, and keep this data indefinitely. I also want to be able to query and summarize the data on-the-fly and display to the end-user. Potentially at scale, but starting with a half dozen POPs each serving thousands of users.

Today, literally, this is all stored in graphite/carbon and works quite well actually considering it was easy and free. What is a better solution for this? I don't expect a turn-key solution.

I was assuming that Prometheus would be the way to go with this. I thought it had the redundancy and multi-site aggregation that I am looking for, but apparently not?