AndyR, store the original AVCHD folders (a copy from your camcorder's storage to a hard drive) and not just the "stream" folder but all of the files. You really should store a copy too (meaning you end up with 2 copies of the AVCHD files) on at least 2 hard drives.
Store at least one of these hard drives away from your primary residence (maybe with parents, bank safe deposit, secure place at work, etc). This is the fire & flood-proofing piece. Home movies are precious that will grow in (personal) value as each year passes. You don't want to lose them because you didn't use some kind of backup... especially with hard drives as cheap as they are.
The reason to store the AVCHD originals is that there will come a time when you might want to compress them into something better than H.264 (when that comes out). Going back to the originals will maximize the quality of those new renders in the future. Recompressing your H.264 renders is going to sacrifice quality. 10-20 years from now, such a (latter) option might have you on the third, fourth or fifth generation of re-compression. It will be much better to be able to go back to the originals for those future codecs EVERY TIME.
OK, so now you have a hard drive(s) with all of your AVCHD files and an off-site copy of that hard drive too.
Organize your AVCHD by shoot dates. For example, I name my folders with date ranges so that I can come back to them later. If you want to re-render your child's 1st birthday, you'll easily be able to find the right original AVCHD.
As you shoot new AVCHD, I find it much more convenient to use a tool like Chronosync to update the latest AVCHD folder (with the new footage). That kind of tool also makes it very easy to regularly update your off-site backup.
iMovie is OK for AVCHD but I became frustrated with its limitations and gave FCPX a try. I feel like FCPX maximizes what I can get out of the AVCHD my camcorder can shoot (for example, FCPX can handle the Dolby Digital 5.1, 60fps video, etc).
I've got a workflow where I use a tool called Clipwrap to do the conversions from AVCHD to ProRes, then use FCPX to do the editing of the ProRes files, render back out to ProRes, then use Handbrake to render a small final version (hiprofile preset) for itunes (to flow to
TV3).
Tools like MetaZ or MetaX are great for tagging those files for iTunes storage. I tag them as "TV Shows" so that all of our "home movies" can be organized in
TV by year. This also works very well making them on-demand and convenient whenever anyone wants to see anything we've got.
Again, backups are important... so consider a main hard drive(s) for storing all of your video media as well as a backup hard drive should the first one conk out. Again the latter should be stored off-site if at all possible.
If you have nothing to start with, you could possibly get by on just 2 high capacity drives to cover both backups (storing both your building library of AVCHD backups and your iTunes video media) on the same drive, then backing them up to the other drive. High capacity hard drives are pretty cheap.
Depending on how much you care about quality maximization, you may not need FCPX and thus Clipwrap at all (I just prefer them because I find iMovie too limiting). I do think a good tool like Chronosync is well worth it (for camcorder to hard drive and then hard drive to backup hard drive); it makes it much easier than manually doing those updates.
IMO, iTunes plus
TV3 is THE way for home movie management and playback.
