So I've been thinking about storage solutions as well, and I have finally come up with a good solution for me. I hope it helps you!
Since the events and projects accumulate in my FCPX, it'll get very laggy. So, I got a 3TB LaCie Porsche Design External Desktop Hard Drive and Event Manager X. On FCPX, I move all unused events and projects to the hard drive. Then, I use Event Manager X to move all unused events/projects into an alternate folder titled "unused event" or "unused project". These don't load when FCPX loads.
For the finalized video files that are eventually uploaded to youtube: Once they are uploaded, I delete them because I can just recreate the video with the project files I have stored.
Also, to reclaim storage space, I delete all render files for both projects and events, which can be done directly in FCPX.
If you don't use FCPX, then the details will be slightly different.