It looks pretty good. I have a little Canon SD-600 which I got because it was the littlest thing I could find:
http://www.dpreview.com/reviews/specs/Canon/canon_sd600.asp
It doesn't have much manual control, but it's really fun and easy to use for snapshots. And the tiny size lets me carry it around anywhere without even realizing it's there. I don't think it would meet your requirement of adding a wide angle lens (is that what you meant by "landscape adaptor"?).
I also like the Nikons a lot, probably because the CoolPix 900 was my first digital camera (bought it nearly 8 years ago!
). I have a 5700 now which I use with Nikon's wide angle lens frequently. It gives me full manual control, although some people don't like the Nikon menu system.
http://www.dpreview.com/reviews/specs/Nikon/nikon_cp5700.asp
It's a discontinued model, was replaced with the 8800 (which may have also been discontinued?)
http://www.dpreview.com/reviews/specs/Nikon/nikon_cp8800.asp
Looking at the specs on the 630 and 640, I would say that 8 megapixels (the 630) will be plenty of resolution. I would question whether you'd see any image improvement on the 10 megapixel 640, considering the quality of the optics on a consumer camera. As far as I can tell, that's the only difference between those two models. If so then I'd save a few bucks and get the 630.