Megapixel count is overrated. I don't think one needs an 18 MP sensor to make professional grade photos when the end use is displaying the photos on a website. (My opinion is that pixel number doesn't correspond 1:1 to dpi count in a print.) And if the sensor is smaller than APS-C, then the extra megapixels, like more than 10 MP or so, aren't really making it any better.
If you want to prioritize smallness, this is especially doable if you are ok with a prime lens (fixed focal length), and you can use a mirrorless camera with a wide-angle lens.
Some examples might include:
- Sony NEX or a5000/a6000 series (APS-C) with the Sony 16mm or 20mm lens, or Sigma wide-angle
- Olympus Pen E-PLsomething or E-Psomething (micro 4/3) with a prime lens (17mm, or Sigma wide-angle)
- Canon Powershot G series, like the G12, and there are models with larger sensors (G7X ? I haven't tried it)
- Canon Powershot S series, like S95, S100. These are "just" a ~10mp point and shoot but with a reasonably fast lens and a nice control ring that makes using the camera more intuitive IMO.
Basically, I think there are lots of cameras that can take a good picture if you get along with the user interface, but the handling varies among them. Some of them are easier to control than others, some have more focus/shutter lag (which may matter less if your subjects are static) and so on. I have never used a Ricoh GR, but IMO certain cameras become cult items because of their maximum specs, while the reality is that there are a ton of other cameras with 90% of the spec that can make essentially the same pictures.