Hello. Always try your best not to shoot in Auto WB. Pictures #1,#2,#3 looks a bit dull. To make your pictures look more warm giving it the 'homely' feeling, shoot in Cloudy WB. If you want your photos to look cool, shoot in Tungsten WB. And from the looks of the photos, it looks quite noisy too.
I really like #4, the rich vivid colours and lush sky makes it very inviting. However, to improve further, i felt that you could have better framed your shot. Framing your horizon almost right smack in the middle of the photo doesn't give your photo much focus. So try to either have 1/3 of the ground or 1/3 of the sky.
the sky looks slightly grainy in most pictures. HAHA! Ya, even though your ISO is set to its lowest, leaving the shutter open for prolonged periods ( more than 8 seconds) will cause noise even if your ISO is low.
To combat this problem, you could use the Long Exposure Noise Reduction feature in your camera. They do a decent job in significantly reducing noise in your photos.