Your camera is fine and you're not going to get a better sensor without spending copious amounts of dollars for basically zero gain for what you want.
Unfortunately, modern cameras don't have the ability to pull in the range of light we see with out eyes into one exposure. Our eyes scan very quickly and combine multiple images into what you see and your brain interprets it as one. Cameras get only one image, because of this, they are somewhat hamstrung.
This is why some people have made a big deal out of HDR photography. Combining a minimum of 3 images (one as a correct exposure mostly for mid-tones, one 3 stops lower for shadows, and another 3 stops higher for highlights) in photoshop (looks ordinary) or photomatix (far better). When done tastefully, it can look incredible, getting as close to representing what you saw as possible. On most occasions it is overdone and looks horrible and because of this, many people who love the art stay away from it because the bulk use of it is overdone. But I digress.
If you're not doing so already, make great use of the recovery slider. It does a pretty damn good job of pulling back the clipped highlights and crushed shadows. Due to the way digital sensors are, if you can help it, it is best to err towards slight overexposure than underexposure. This is because more detail is recorded in highlights than shadows and the highlights are easier to pull back and restore detail.
Using your train shot as an example, the sky is horribly blown out, perhaps beyond saving. It may be worth trying to see what the recovery slider can do. You can then apply a gradient overlay and mask out all but the sky (maybe some of the hill and trees too), making it look nicer, if there is any detail retained at all. Otherwise, this is where a GND filter would have helped you out if you don't want to work with multiple exposures.
Check out what I mean
here.
Hopefully this helps a little. Please don't read any of the above as condescending or similar. It may seem like it, I'm just trying to help not knowing your current photographic experience level, plus it can help lurkers or whoever else.