#1 lacks punch. It has an overall dull quality with little detail below the low middle range. It looks like it was underexposed and you tried compensating in post. I was able to make it look a little snappier in PS CS5, so you might want to play with it some more. #2 is a bit better. There's a little clipping in the highlights but it's not bad. But it too could benefit from tweaking the levels some. The third one shows a lot of clipping in the upper levels and is too skimpy on the midtones for my taste.
I question whether the camera you're using has the dynamic range to keep the high values in the snow from blowing out and/or the low values from getting blocked. Snow is tough to shoot well and it takes a lot of dynamic range to pull it off. There could also be an issue with your monitor calibration.
I am not clear on what you mean by lacking detail in lower mid-tones on number 1, and would appreciate a bit more insight into what that means if you wouldn't mind. I did do a comparison side by side in CS5 of the JPEG versions against the TIFF originals and the JPEGS were definitely flatter so I added some contrast back into them to get them looking closer to what the original TIFFs look like. Photos used in this first one (15 shot stitch - non HDR) were not underexposed or overexposed so hopefully the cause of the dullness was in the JPEG conversion.
Third one I agree looking at it (though JPEG conversion did not help either), it was too bright and this hides some detail in the snow, so I have adjusted brightness, levels and curves.
Camera used in a Canon 40D which I thought has decent dynamic range at ISO 100, and I am not sure why you are seeing clipping as my histograms on both original TIFFs and the JPEGs I originally submitted do not show clipping. Not sure if this is something "caused" because I am using a wide gamut monitor (also calibrated about a month ago)
Thanks for replying.