I loaded up Sunset Valley and tried the "shell" I saved to the library on the 60x60 lot - 15 Summer Hill Court and didn't like it as even with flattening the lot it still looked a little bumpy. Not sure how to explain.
I decided to fully rebuild. I'm happy that I did as it came out more like what I was hoping I could get the main floor to look like.

I tried to keep 12 grid spaces on both left and right sides of the house and was able to accomplish that. There's 8 grid spaces in front and 26 or 27 grid spaces in the back of the house. So tons of space for any outdoor buildings, pool, playground and/pr anything you'd like to add.