Velocity, I like the first one better than the second. Is the green really that color or did you bump up the saturation a little? It seems a littl too green to me (but that could be monitor). I would also like to see B/W with a pretty high contrast...I think that could make it a bit interesting. Also, if you can get back there, you might want to try angling your camera up higer...get more of the wall and less of the stairs.
As for the second one, I like the wall in it, but I feel that pier and beach somehow detract from the wall, which I'm assuming is really what you want us to see...especially as you mention in your post that it's the curve of the wall that excites you...show us that...walk around and look at it from different angles to figure out how best to convey the curve
Hope that helps.