I don't think smaller is the way to go here. Smaller means more, and more isn't necessarily good. That, and smaller raindrops will just make it look like a scurry picture. No, if I were to voice my opinion about the first and third one, I'd say you should use the Monsoon model as fladder suggests, only blow it up too a very large size, doing this will spread the raindrops out and make them look rather realistic. Fooling around with that feature may make for a good effect.
That, and I honestly think it needs a better center of focus, not entirely sure what but I just get the feeling "where am I supposed to look" when I look at the terrain. That and I personally think the terrain is too gray, I'd say you should thin out the fog a little go give room for being able to see more, and experiment a bit with the gray fog, possibly giving it a slight blueish touch.