Small, light, affordable, go for micro four thirds as suggested above either Olympus or Panasonic. The compromise is that a smaller sensor, whilst giving a smaller camera with smaller lenses gives you a much deeper apparent* depth of field so if you want those shallow DoF shots (e.g. portraits with a blurred background) you need a lens that has a wide aperture (f2.8 on MFT is effectively f5.6 on full frame). On the other hand that is great for lanscapes where you typically want everything in focus front to back.
(* before someone mentions it and with apologies to the OP for the nerdiness, the depth of field is the same for the same focal length but for a given angle of view, an MFT lens is half the focal lenth which gives twie the depth of field, e.g. a 25mm lens on MFT give the same field of view as 50mm on full frame).