I use an old Olympus XA rangefinder (7.5 oz.). In my opinion they were (and still are) one of the best lightweight cameras for backpacking. You can still get them used if you look around. Check with NYC camera stores. Compact, light, and excellent optics. Manual focus. It's auto exposure but can set your preferred aperture. It also has a +1.5 stop "backlight" switch. With a little user smarts on your part, the XA will out-perform all the fancy automatic stuff on the newer cameras (e.g. Stylus Zoom). The automatic stuff just screws up photos. I can never figure out what the camera is doing (and it is always the wrong thing). For 90% of backpacking photos, just put the XA on f/8 or f/11 and set the focus to infinity. The XA is very rugged but not waterproof. I've had mine since 1983! Haven't found a better packing camera yet.
Disposable (excuse me, recyclable) cameras are great for short trips. Some of the shots on both Sierra trips were taken with recyclables. Again, I know what the camera is doing. If my subject is more than 4 feet away, and in reasonable daylight, I know I’ll get a decent picture. The optics aren’t perfect but for snapshots and web pages the quality is more than adequate. With recyclables I don’t have to worry much about damaged or stolen cameras. They are fantastic for harsh environmental outings like tropical beaches. When backpacking, if I need to take more than two or three recyclables, or I need superior optical quality, I’ll usually opt for the Olympus XA and roll film.
Digital cameras, for the moment, are too heavy and expensive for me. The also have limited image storage. This may change soon and I guess that I’ll have a light digital camera in my inventory in the next two to three years. For the time being, I’ll use my XA and scan photos in.