Then I blew it, and saved over my BUILDING world with another world, and had to go back to a save that was from a couple of weeks before I had made some BIG progress on the apartments themselves. Since then, though all the rest of that world was just like I left it before, I haven't been able to get back in and work on the apartments...sigh.
When I downloaded the Movie Stuff Pack last night, I decided the perfect place to put my first viewing room would be in the basement of that building, so I went in and got the activity basement updated to where I wanted it (pretty much like I'd had it done before), then added a second basement level with the movie theatre in it. I really like how all of that came out.
Before coming in here, I completely deleted the old topic, and started over. The pictures below are of how the Magnolia Elder Housing lot looks right now. Tonight I plan to start adding in the actual apartments. That should go faster for me than it did the first time, because I have a better idea of what I want to do, than I did the first time around.

Photos from 01/15/16...
Photos from 01/16/16 (three layers of basic apartments)...
If these pictures look identical, they pretty much are, except that they actually are three levels. I had previously made each layer of apartments somewhat different for the different Sims involved. This time I decided to go with identical basics (mirrored in the two units), and I'll just decorate with the Sims' own belongings in their apartments. I should have taken at least one side view, since the added balconies at the center of each unit do change the profile. Next time I'll show that.
I'll have to experiment with locking bedroom doors and choosing beds, so that the Sims who don't belong in each apartment will go home (or down to the community areas) at night (or in their off-times, if they have night jobs). Since they're all Elders, they probably won't have any jobs, though I haven't decided on that yet.

I've noticed that though there's plenty of food down in the basement where they all are, so far, there's also workout equipment and the swimming pool, so every one of the Sims (including me) has become more fit than when the group was placed! Nice!