I ruined Diana's house by mailing her horrible furniture and giving her multitudes of ugly bugs, so I am inclined to pick someone else's home.
Aurora's. Love the coziness of it. Its like a cabin in the northern lights.
I would say that a topiary project (round or square) would probably fit and look nice next to the house :) If you have them unlocked from weeding day, they look pretty good! Or maybe a flower clock, idk if it would fit.
Secret bases were a really fun feature, for me at least! I loved decorating it and the fact that it was literally a cave was quite enjoyable to me. I agree that end-game content is a must. X and Y did a good job with the Friend Safari and such, but didn't quite give us a REASON to fill up our...