Very nice images, but I like the third one best, for its sense of reality and soft tones. The first indeed reminds of an old (dirty) oil painting, but I'm not keen on the rain stripes. They're too much in one plane, I would go for localized small particle TG2 Y-stretched clouds. In number three I would decrease the foam displacement to half what it is now, for the scale I think it is just too thick. The ship is great, by the way, very detailed.
---Dune