I'll visit right now, let me see if I can come up with any ideas, I know those empty spaces can be pesky.
I'm back with ideas: I'm unsure if this area was meant to be blank or filed in but I think a cute little stand or maybe a place to park bikes would look cute here
Once again I didn't know if this place was supposed to be left blank or filled in but some fishing stuff would look cute here, like a fishing pole and a chair like someone went fishing, and there's some fishing tourney things too and then there's some fish you could catch and put here too like someone caught something and they were displaying what they got.
Finally this area, this is the area that I'm assuming you wanted to get filled up in the first place, well well well have I got some ideas for you, I'm surprised you didn't turn this place into a eating area of sorts, what about a bakery? seafood place? fast food restaurant? smoothie place? the list goes on and on honestly I it would look cute if your villagers walked down from the neighborhood here to come eat together. Not interested in a food place? I still have more ideas, Post office, Clothing shop, collection display area, video game arcade, farm, orchard, waiting areas such as a bus stop, sports field, playground, movie theater, music concert, a place based off of your favorite things, a place to represent your favorite villager or special character(example if you love blathers you could fill this place with fossils, study equipment, blathers custom designs and the like) phew.. hopefully one of those things helped, whatever you end up doing with these empty places I hope you come up with something you love!