If you look at "Scenery" box in your polyworks, you can see all sceneries u used on the current map. You also have few checkboxes - rotate and scale. If selected, theyd allow you to do these operation when placing a scenery. Try using it to make the scenery look less copy-paste like :b Also the "Opacity option" under in palette affect next sceneries, as well as polygons - might be helpful to blend in some sceneries that stand out too much.
About the mess i meant sometimes you went a bit crazy (mostly where the ramp/slopes are) and i think you couldve make it look a bit less chaotic, but its still quite well done..
PS. Post your map screenshots without waypoints toogled ON (numpad 8 to toggle on/off) so we can actually see the map xD