Good Morning, In reading the posts here, I think that most of the major points have been made. Choosing a camera is difficult, however with the available choices it is going to be difficult to make a bad decision.
I started with the K100 (although I had a Spotmatic II in 1970) and about a year ago upgraded to the K20. I tend to run a camera generation behind - easier on the check book, but lenses are what make the camera system. The deciding factor for me was the in body image stabilization, especially in that for landscapes, Canon /Nikon did not offer any stabilized wide and ultra wide lenses (so it was an easy decision). It helps me, since I work during the day, so I take pictures (landscapes / cityscapes) in the late evening and at night - not always having a tripod with me. Also, on business trips, I am not trying to pack a monster body & lenses. Glass, size and build quality brought me to Pentax.
The 10-17FE, 12-24, 16-45, 31Ltd and 55-300 cover everything. Wonderful lenses, great colors, excellent quality glass, and I could afford them (even if it took me 5 years to acquire all of them).