Do you mean like this:
HOSTED PHOTO
please log in to view hosted photos in full size.
Workflow:
Spend a bit more time than I did to get better sky blends!
1. Do a levels adjustment, the right side of the histogram is lacking in contrast.
2. Create a polygonal lasso selection from the left third side, staying VERY close to the transition edge.
3. Feather the selection by 60 pixels (this number depends on the image size)
4. Add a levels adjustment layer and use the middle slider to blend with the rest of the image.
5. Use the Pattern Stamp and the Clone stamp to blend in the clouds.
6. Use the wagic wand set to 15 tolerance, anti-alias on and select the sky only.
7. Feather by 60 pixels again
8. Do a levels adjustment layer again and move the sliders to touch each side of the histogram
9. Inverse the selection
10. Do another levels adjustment layer again for the foreground and move the sliders to touch each side of the histogram
Tweak each adjustment layer to your hearts content

Next time, shoot in MANUAL so the in-camera exposure does not change (which seems to have happended here). Set the aperture and shutter speed to a middle tone area of the scene, middle left of the scene here. Meter there and focus there (then set focus to manual) and then DO NOT change anything! Shoot from left to right and your images will blend first time round.