Yeah, I'm trying to graduate from building boxes too. I can definitely do those.
I built a great large and boxy house in Brindleton Bay that I actually like a lot. It's just that there's a time for boxes and then there is trying to build more than a box. Sometimes I've downloaded and I very much appreciate the builds that I added in that way. It's just that I felt myself getting lazy about building. Also, there's a feeling after you've built a space that it's definitely yours.
A few builds that I've downloaded have settled into my game or they have been lightly edited to do so (which I would never re-upload). Other times, I got the feeling that a space wasn't quite right for the game I was playing. I tore down one restaurant download even though it was pretty nice because it felt like that. I'd rather build something myself on that lot.
Anyway, I don't judge what anyone else does. Building with blueprints or plans would be interesting. I've typically built without plans by installing rooms that I need and then filling in the blanks or with some other central concept. In the build that I shared photos of above, I knew that I would build a spa retreat, that I'd try to emphasize the view and that I'd also build the porch. I figured out the rest by playing around. I'm totally cool with mixing it up and yes, I count myself as inexperienced in this version.