Just a suggestion
G'Dy, been away with surgery for 3+ years, not an expert like others could suggest, but my just a few.
1st, love the sky..
2, grass textures needs possibly re-scaling down, or use something more defines, add some flowers, and longer weeds, near edges and trees.
Maybe get rid of that big tree, (a bit too large), probably lots of poly's as well, most parks would/could have just large bushes nearby, places like cgtextures.com, has alpha planed images, that could be used..check the nature area.
Building edges/walk ways usually dont follow straight lines when meeting the ground, maybe add some undulations, dirt piles, plants,rubbish etc.
If you have control over the building interiors, vary th position of the curtains, some would be closed, 3/4 open, 1/2 open etc.
Hope you dont mind these suggestions, have been following you for a while, and doing a great job..
I have some small plants I have made/modified, let me know if you would like some..