I've pretty much said everything in the topic summary but i suppose there are some extras i can mention. I have used the puzzle pieces in the Transport Network Add-On mod which adds a nice bit of variety to elevated rail, as well as Deadwoods Elevated Rail Shops. There are, however, even using both these mods, patches of grass left underneath the elevated rail which just dont seem to fit in with the urban surroundings and elements of repititon.
If anyone knows of any additional mods i could try i'd really appreciate the heads up