I would move all the houses onto one island, and make a field of flowers from the bridge down. (on the top island)
Flowers make almost anything beautiful (Especially if they're hybrids. Avoid orange.) and they take up space.
Your beaches and west area are VERY similar to my town! You can visit my dream address if you want. One thing I like about this map is that there's room for pwps pretty much anywhere. That's a very interesting spot for a town hall. Could be a lot of fun making paths around that area. The retails isn't in the best spot, as its really far from the dock. Still a really great map.
I agree with what these guys are saying: move all of the houses onto one island. I would chose the bottom one. As to your question about the paths, I don't think that you can finalize paths until you have all of your villagers moved in. It takes forever to get them into the exact spot that you want, mine usually end up just slightly off. But if you're willing to put in the time, then I guess it's a different story!
Since you're moving your houses to the bottom island, a PWP suggestion: you could put a campsite towards the bottom of the top island on the left hand side, it would be nice and secluded.
A suggestion for a little later down the road when these are available, the Police Station and the Cafe' PWP's would be nice additions, I'd put them near Re-Tail.