Try number 3... Maybe not mentioned before, but I also want to share the photo library with Jen. So I followed this KB article to create a mounted image.
The mounted image seemed to work. But I can only see photos that I imported, and Jen can only see photos that she imported.
There is this warning "Sharing iPhoto Library not recommended" in this KB. However a google search returns a lot of ways to share a library. Even this warning is unclear to me. I think it applies to pre iLife 08 versions (7.x) of iPhoto. Besides recommending not sharing contradicts the first KB.
In anycase, I'm going to have to check the groups, owners, and permissions of all the files. I'm guessing that since Jen and I are not in the same group we simply can't read the others photos.
Finally, since I've now created a shared image that needs to be mounted - I also followed this KB article which details how to make this mounting happen automatically at start up. But this didn't work for me when logging out and logging back in. Maybe on full boot it will - I haven't tried it yet.
Since this is so hard I'm guessing Apple doesn't think that a single laptop (iMac for that matter) would be used as a "family" computer. In my house, the family computer is used by at least Jen and I. We strictly use a single place on the computer to store ALL of our data. On our PC we had a folder at the root of C. We had links inside My Documents to that folder. This really helped backups and it was great when I wanted to get all our data to the mac - it was all in that one folder on the PC.
We are attempting to do the same thing with the Mac's users/Shared directory. On the pc we had a directory called photos under the top level folder. I wanted to point iPhoto at that same dir which now exists as users/Shared/photos - but that is not to be...
Ah, but this post is titled iPhoto Library Size - the size is way down. It is at 27 Gig. Which is a lot better than 104 gig. It is so different that I'm tempted to redo that first create to see if it is repeatable.... In any case, 27 Gig is "only" 3 Gig of overhead. I guess that the price one pays for quick thumbs.
I wonder if this would all be a lot different if I wasn't an engineer who uses Linux/Unix all day. I guess I'd likely show up back at the Mac store. Wonder if they'd make this work. Time for another experiment.