When I look at my town, I forget I have a lot of trees. But then I think about it and realize I do. I also had perfect town, until I decided to put a bunch of decorations on the floor with objects that are considered trash. XD Anyway, I'm saying I understand how you feel, and here's what I did:
First of all, I lined the entire upper edge (by the train station) with cedar trees. The edges of town need a border as far as I'm concerned, and trees and bushes are perfect for that. It's also out of the way, so you're not constantly dodging them. I have paths everywhere, which people don't like, but it's a lot of open spaces with paths. I hate when people have mazes of bushes and trees and you can't walk anywhere without running into something. XD
Second, I planted at least 3 of each type of fruit tree. Most of the time, I bundled them together in some design. Hard to explain this one, but when they are in little clusters, and most of the time also surrounding specific PWP's, then it's more reasonable, because they are organized, not just in the way.
That's my third tip though, look to see where PWP's or houses are, and see if you can put a tree on each side, just to add a little nature around it, and decorate it that way, also including trees.
And fourth, look at your walkways. If you have paths running between houses or buildings, see if you can put some trees along the walkway. I did this with my perfect trees and town fruit that I wanted to have a lot of, and in moderation it helps also.
OH, and the beach is also a great place for a row of trees along the beach. Although I'm not sure if those trees count towards perfect town. I don't see why they wouldn't.
Last thing, do you want perfect town for a while, or forever? If you just want to get it and go the 2 weeks or whatever to get the golden can, then just plant a bunch of trees, get it done, and later you can chop them down. That's an option, obvious one, but worth mentioning in case you didn't think of it.
