In April I upgraded from the K100 to the K20 - the price was great, however I kept the K100. Where you go (what next model), I think would be what you want the body to do for you....
I wanted ISO 100, plus the 2 second mirror up was on the same menu as the bracketing (can only select 1 and not both). Going to the two wheels were a plus, and the increased resolution (6 to 14MP) did help some on stitching (portrait) along with cropping to a degree. Auto focusing is better, but not to the extent of the K7 (and I hear that the KM/2000 being newer is between the K20 and K7). Also, the orientation sensor was nice, after having to flip all the images by hand on the K100. Having bracketing on a separate button is nice (along with a choice of 3 or 5 frames). Also the image buffer storing more than 3 images helped when I was bracketing, not having to have to hold a shot while the prior shot was being written to the SD card. Not having the AA batteries is essentially a wash, although the rechargeable is nice - and I still have to get a spare battery sometime.
I do find that I like the access to the information on the top LCD (KM and KX do not have it). I also like the couple of additional shooting modes - the P and the green button does make things nice. Thus, for me the K20 has turned out to be the right model to move up to.
The additional size was a concern, however - I seem to be shooting much more on a tripod at night now, and even hand held the additional 5 oz is nothing at all. I have several images that were taken with the K100, and I only wish that I had the K20 for them.
I got a great price - $650 at the time and it came with an extended 3 year warranty, so essentially I am set for quite some time. Its nice to read about the K7 - but all in all, I feel I found a smoking deal that has worked for me. The K7 for as nice as it is, is probably not twice the camera for twice the price. I figured that at the time, I would need to wait an extra year for the K7 to drop in price to the point where I would consider it. With the K20 there at my price point, I just went ahead - and essentially have gotten an additional year of shooting on a better body. I used the K100 for almost 4 years, and I am expecting to be happy with the 20 for another 4 years. I just was looking at an image in PhotoMe and I have about 1800 images on it, so that is about 300+ per month. Color me happy, it fit very well for what I was looking for.
I have taken it on several business trips - caught several very nice shots of the harbor in San Diego and over on Coronado Island, along with some sunsets. It travels well, and I have settled on 4 lenses and that is what I use. It has cost me though. I needed a better tripod and ball head, so I did go out and acquire a much better one replacing my old plastic and aluminum on which bit the dust. So, overall I am set....
The K200 is a K10 repackaged within a K100 body. I like the K100 very much, and I think that its a wonderful camera - and it does have the top LCD that I like. So for me its either the K20 or K200 depending on what you like - since your going to be using it...